If you're going after name brand stuff like record and dura ace of course its going to sell high, I've even seen arabesque cranksets sell for $60+ I'm not saying you may not get lucky sometimes, just doesnt happen very often. I only got about 12$ or something like that for a 7402 Dura ace RD on ebay few weeks ago, typically they will sell for around $40, so it may not be a bad time of year to hunt for deals. Or you can just use my approach, buy stuff thats so ugly no one else will bid on it, I got a 7700 DA crank that way, 10 bucks cause it was scratched to hell, i just sanded the thing down and polished, oh and I just bought this, basically for shipping:
I needed a 60mm stem, im not gonna pay $30 for something that looks pretty when it works all the same!