Steve,
The build quality of my Soligor lenses is very good and equal to Pentax M42 in this respect. The IQ varies according to who made the lens for Soligor and the original cost. My 70-220mm f3.5 C/D zoom is a good performer, although heavy at 3lbs. It does have a tripod mount and is all internal for focusing and zooming. I have a couple 35mm f2.8, T4 lenses that are decent, but they aren't the cheapest Soligors either. It is easy to trash a lens, but you should try one first.
Dave
Originally Posted by stevebrot 
I have wondered why there is very little Soligor glass on the used market now. Maybe they all fell apart? Strangely though, back in the late 60's and early 70's, Soligor was a major player in the 3rd-party lens market second to Vivitar. Apparently they had good marketing and/or pricing.