Not a lot, tbh. The curious thing about Base Set Machamp is that all of them (that were released publicly) were printed with the 1st Edition Stamp, even if they weren't actually 1st Edition. The cosmos version was included in the Base Set 2 CD-ROM Starter Set, technically making it a Base Set 2 card. Base Set 2 never had a 1st Edition print run.
In good condition, one might be able to get about $30 for it (ungraded). In this condition, however, you're probably looking at closer to $8.