Pricing depends on availability where a guy is I guess ?
Around these parts "good" cores are getting very difficult to find ? let be when you do and dis-assemble only to find already .030"/.040" or even .060" over ?
or,
buy bare blocks with std Bores, then only to find main caps from something else, rusty bottom dwellers, cracked/broken ears, and on and on.
A few years ago, we used to stock 440 & 400 cores as part of the Business in offering BB Mopar builds, but with a core "exchange" requirement of equal prior Bore, and we placed a VERY Hefty $2K price on our cores having been thoroughly cleaned/checked over, Mag'd, Sonic Tested, etc., etc.
The whole idea being we did NOT want the money, nor to have to charge the $2K .... we wanted GOOD Cores returned BACK !
Well, you guessed it....
How many times do you dis-assemble the returning "cores" from Customers only to find JUNK.... and it was NOT good Business to then insist upon the $2,000 Core Charge be paid by long term repeat Customers.
So eventually all our "good" cores got depleted, with the returning JUNK Blocks filling the metal bin, and with us eating the time over and over again until done.
Morale of the story....
Make sure it's GOOD before you pay for it... no matter what you PAY !