The only one Promaster lens that I may consider buying is the 100mm f/3.5 macro lens from them. Actually, from what I read, it is made by Cosina. And you can find the same version with a different brand such as Vivitar, Phoenix as well as Pentax.
The lens is a 1:2 macro lens but shipped with a extension to make it 1:1. Reviews on the lens is quite good in image quality. However, the body build is very plastic like a toy. And it has a nickname of Plastic Fantastic.
I believe the autofocus of that lens is slower, but for those who use it as a macro lens, manual focus maybe is their choice anyway.