I paid £4.60 for a 58mm SLR lens off eBay this week, and coupled with the M42 adapter I now have a prime lens for the grand total of £12!
Yes I have to do everything manually (But there are adapters out there which have the chips allowing the camera to 'read' the lens) but I love it. Photography, back to it's roots ...
I wish (sometimes) that I could go back to the manual system .... just a wee bit more control.... well .... quite a lot more control really!! Good buy by the sound of it.