Since it sounds like this is your first engine build I am going to give you a few tips I have learned from my experiences...
First for your questions...
The valley pan is $15 it doesn't come with all gasket sets but its a gasket and I would change both intake and exhaust gaskets -
http://www.ebay.com/itm/221346979384?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT, I pulled an exhaust valve out of an engine with 80K miles on it, dropped it and it shattered like glass, I change everyone now, lol, I have used them valves in the link and they work, for the price they can't be beat...
The first thing to realize is machine shop/engine builders need to get paid for everything they do, even order you parts, plus they aren't going to shop around too much for a great deal, so buy your own parts, I found Falcon gives the best prices, you have to call with a list and ask for the best price but I have yet to find the company that can beat them... 601-693 8282.
Next pull the engine apart your self, its easy to do and doesn't take many tools (balancer puller is about the only special tool some may not have and its just a 3 bolt grip for the 383). Heads off, crank out, pop the pistons and rods out {I have a press so I press the pistons off of the rods too, that is one of the time consuming things that a machine shop will have to charge you to do}, save all the bolts and parts. Now take the heads, crank, rods, and block to the machine shop, have them tell you what size the block will clean up at and start ordering the parts..
My father just had a 383 done about 2 months ago.
I bought all the parts and took them to the machine shop for him, we stripped the motor down to heads, crank, and rods/pistons, I stripped the heads and wiped them down, I pressed off the pistons, I checked the bore and it would easily clean at +30, I also checked the crank and it was good at std but the motor had miles on it so we decided to turn it -10/-10, so I went through and ordered everything..
+30 teflon coated L2315nf pistons with hastings rings $370 shipped, melling hv oil pump, clevite rod, main, and cam bearings, fel pro gasket set, valley pan gasket, valve set, rockers, rocker shafts, valve springs, melling distributor drive and brass bushing, brass freeze plug set, push rods, 2x roller Crane timing set, lunati voodoo cam and lifter set, fuel pump, and ARP head, main, and rod bolt sets... I even went to CAP auto (best prices on plasti kote) and grabbed 4 cans of #228 primer and #226 chrysler engine paint..
We went with new rockrs and shafts because this motor was dirty and had a lot of use, a lot of times you can reuses them, I think the set for both heads was like $200...
I (OK, I had my 2 sons do it) cleaned and stripped the timing cover, valve covers, balancer, intake, and oil pan, I primed and painted them with the fuel pump and new oil pump, all of that stuff is the time consuming easy to do stuff that a machine shop is going to charge you 50-90 an hour to do...
So now I drop off a stripped engine block, heads, crank, and rods. With all of the parts ready to go, painted and prepped. My father spent just over $2000 and that was for everything listed above plus a stainless bolt set and a rebuilt 750 holley from Promax (go to his specials page he always has them on there, I just call him and ask what he has for me, I will take his rebuilt carb over any new holley available, they do GREAT work!, plus you tell him your cam and motor and he will make the carb pretty much bolt on and run!!!)
So now that may sound expensive BUT, we used decent parts, you can buy jobber cam, timing set, pistons, etc and use your old carb, you can cut that price in half, we have done full rebuilds with $800 of parts. You can reuse your old head and main bolts (I like new bolts especially main and rod, but I have reused head bolts in the past on some motors with bb mopars, they have 3 rows of them they don't have issues), you can reuse your push rods and dist drive, just depends on how far you want to go, to me if its a nice car nice motor and you drive it, go all the way...
That 383 runs excellent by the way, we went with them flat top pistons and 10230701 cam, it had a nice idle, and man did it wake up, it was a stock road runner motor and had some pep before but was tired, we didn't dyno the motor (another thing the machine shops don't do for free), but it was potent for sure.
So the machine shop charged...
$95 to work the crank
$350 for the block, clean, mag, bore, hone (price includes mag clean for heads, rods, crank also)
$220 for the head work thats 3 heli coils, comp valve job, clean them up and port match intake, and assembly
$450 for the build.
So the machine shop total was $1115 the parts total was $2020 (if I remember correctly) so for a bit over $3K that motor is done and done right... Now we do a lot of business with our machine shop and builder so we get OK pricing and he treats us good, he cleans up our heads, matches our intakes, etc. I can tell you first hand that little bit makes abig difference, he had a 6 pack motor that he dyno'd at just under 400hp, then he cleaned up the heads matched the intake and re dyno'd it the motor picked up over 25hp!!! He changed the crank/rod set for a lightened/balanced 330hp crank/rod/balancer and picked up another 40 hp!!! I would have never believed it if anyone ever told me that, you clean up a 6 pack intake, swap out the heavy rods and can get 450 with stock pistons and cam, then he changed the cam (it had under 500 lift), and pistons (a bit more compression) and got right around 500... I had him build my 6 pack the same way except I had promax do my carbs
...
So hopefully this helps you, it sucks to do an engine twice, lol I have been there, if you are doing a minimum build then you can save some in some places, but you are better off waiting until you can afford to go all the way, I have seen guys reuses timing sets, it is just a matter of how far and how much you want to do...
My cousin built his 440 and reused the old oil pump, timing set, cam and lifters (plus bolts, dist drive, etc) he only changed pistons, rings, gaskets, bearings, freeze plugs, and pickup screen, the actually never sent the heads in to the shop, he pulled them off ran them through the parts washer and put them back on the motor. I thought it was crazy, but he had blow by, the motor was getting a bit tired, so he wanted it freshened up, it is still running, he has it in a 71 satelite/rr clone 4 spd and it starts everytime he turns the key. The problem I see is he still spent $1700 or so for $3000 my father did his motor complete top to bottom...
To each there own, good luck with your build, one more note, more important than all the parts is the builder and machine shop, I use a builder that works outside the machine shop but they work together, there are good all in one shops out there but I noticed the race engine builders seem to pay a bit more attention to detail, plus when the machine shop knows its going to the race engine builder they tend to make sure everything is perfect, if you are putting the motor together or even if they are maybe they can get away with a small fudge here and there, but if they know the race engine builder is going to be mic'ing every dimension and checking every aspect of the block, heads, and crank they are going to maybe pay a bit more attention for you.
