Depends on the yard, the guy behind the counter, the part, your attitude, what story you can spin, &c &c.
Best one I had was buying an AW4 (for my own information, more than anything else) from a full-serv dismantler that has since folded up its tents and gone home - probably due to some asinine CA reg or another they didn't want to deal with anymore...
They had one lying about. I asked them if it "worked when pulled." He said he thought so, and was asking $200 for the thing. I said "The first thing I'm going to do when I get it home is tear it to bits. I've not worked on an AW4 before, I now have three of them, and I'd like to know more about them before too long."
"I can let you have it as a core - no warranty whatever, except that it's buildable - for thirty bucks."
"Sold!"