I've purchased a number of lenses from KEH from bargain to EX+. Most of them have been manual focus lenses but some have been AF as well. In almost all cases I couldn't see much of a difference between the bargain and EX lenses.
I've also bought a number of lenses on ebay listed a 9 or better. The bargain lenses I've gotten from KEH were in better condition than the ebay lenses.
I did purchase 1 bargain lens I had to return because the zoom would sometimes jam up. I sent it back to KEH no questions asked and they picked up shipping since the lens did not operate correctly.