Heat Insulation/Soundproofing: Not Cityproof

High-ish floor (20+) condo owner facing a busy avenue. Interested in improving thermal / heat insulation as a primary goal and soundproofing as a secondary goal. My understanding is that with interior windows from Cityproof or Citiquiet, both will happen. However, right now budget doesn't quite allow for the expense of Cityproof or Citiquiet, so looking at alternatives-- Anyone have experience with Indow Windows (plexi, pre-cut, self-installed, removable, www.indowwindows.com) or doing something like ordering from 365plastics.com and DIY? Also, there isn't a need really to open these windows so that's less of a concern. Thanks for any thoughts!