As stated in the other posts, I don't know of a manufacturer that makes just the handles. I looked at Gary's post and wow does that HF trim router resemble the one from MLCS (Marvel 40). That one comes as a kit with all kinds of attachments including a base with handles on it and a case. It is reasonably priced (for what it does) and comes with free shipping. You might give it a look. I also made a sub-base for mine to accept PC bushings, as Gary did, but with larger square bases (4" & 6").
If you never made a mistake, you never tried anything