Totally agree. While 100$ may not be that much for some people, I still see MANY flaws in that Zentai undersuit. It looks very fake, artificial, with that all artificial lights and shadows. I've seen some people wear it and it looks very weird with the armor, like they photoshopped it. Not to mention that many parts are out of place - the joint parts aren't at joints but rather at forearm, the spine and butt area is SO high almost at your back. In more than few places it's weirdly sewn. The crotch area is way too high.
But, the worst part is it looks artificial and fake as hell together with the armor. In fact, it often looks more detailed or turns away the attention from the armor itself to the undersuit, which it shouldn't do... It should be a small detail, not area of focus - focus should be on armor. :/
But it's just my opinion, I mean no offense.
While I think that muscle suit is a nice base, I totally understand you that you don't want to cheat and good luck!