What is a cast iron 2bbl intake worth

whenever I think of buying anything there I scout around to see if anyone is selling one just like what I want. I just bought a new battery tester for $280, most other sellers were in the mid $300s to around $425 range for teh same tester and there was one idiot that thought his (IDENTICAL!) tester would bring him over $900??? Really?
I bought a set of slant 6 pistons recently for something in the $60 range for a set of name brand Sealed power ones.,..... how can some think I'm gonna pay $244 for the same set of pistons (no rings) from them? I got pistons and Moly rings from 2 different sellers for under $100 total.