Most of these lenses seem to be available from Russian, Ukranian, etc., suppliers, and about all you can do is to look at their eBay customer satisfaction ratings. It might also be a good idea to ask a few questions, at least to let them know you are serious about quality issues, and assure yourself that the lens is returnable if not satisfactory. Mostly, though, on a lens coming from overseas, given the cost of shipping, you are stuck with what comes in the box.
If you can find one of the lens in a shop for inspection, of course, the matter is completely different. You can examine it in detail, preferably on the camera where you expect to install it with the appropriate adapter ring. Then of course you look for all the usual things: image quality, focus, dust, mold, scratches on the glass, and general appearance. Lots of these lenses are stiff when you turn the focussing ring, and while inconvenient, stiff focussing in my view is not necessarily a disqualification.
With my lens, the Helios 44k-4 58mm, I was fortunate to receive a nice copy, and lucky to find one in K mount so I do not have to use the adjuster ring. If the copy you are looking at is screw mount, as most are, be sure you have the correct adapter for K mount.
With the value index these lenses offer, and their low selling price, I think it is acceptable to take a chance. That was my approach, and I came out great. The overall appearance of these lenses is tough, a little crude in production quality, but capable of taking a beating and still holding up okay. That is the perception you get looking at the lenses. The reality, of course, may be a little different!
Good luck to you in the adventure!
Last edited by ivanvernon; 02-05-2013 at 05:24 AM.
Reason: premature accidental posting