It depends on the condition. I sold one recently for $75 that had extra holes in it and the rear crossmember bolted in instead of being riveted. The front crossmember had been welded to fix a crack. A nice unpitted or slightly pitted frame might be worth $200 to $300.
I think it depends on the area you live in.
I live in central FL. Not to many frames floating around to begin with, and to find one in decent shape. Good luck and be prepared to pay.
I've been looking for one for awhile. I should have kept the last one I had.