Thanks for the good words ya'll! Good points about media getting everywhere, I admit it freely, the stuff gets EVERYWHERE! You should see my dryer at the house, my wife says nothing these days, learned to wash any contact clothing at the shop first, then come home for second wash, but, 90% of the time I'm wearing a blast suit with shorts on underneath, shake the suit off, wash it, hang it up and good to go for the next time!
For me, Rockers are the absolute best Hide and Go Seek place for media to get into, and not want to come out! I use duct tape on the larger access holes, sheet metal screws for the smaller holes, then, blow, vacuum, shake, blow etc it all out, then, when transporting the vehicle more falls out on the floor pans, or, on the trailer deck if that hasn't blown away (this is why I always bring my shop vac when delivering).
Undercoating I usually scrape it off, makes it easier when media blasting the car. Seam sealers I poke at with my scraper, then, media blast what's left, but, the lower seam sealers usually is where issues arise as water collects and sits down low, the upper seam sealers usually are good to go.
I try to keep my pricing on the side of an upper middle spectrum, but provide excellent results in the top notch category. What's that saying, 'A bird in hand is better than two in the bush'? I look at each job as if it was my own, no time constraint(s) or boss beating me up to get it done, etc., that's where corners are cut, etc. Being a one-man shop has pros and cons, as most everything in life; trade offs, etc. I also angle to have everything that leaves my shop is ready for primer, the day it leaves its ready, no sanding, no scuffing is required, surface is about a 1500 grit profile; perfect for primer and a good base to work up from.