Well, Rhino you have definitely come to the right place!
This website was literally created as a means to trade both info and figures of the specific lines that you mention: Battle Beasts, MUSCLE, and MIMP.
As far as trading Mutant Mania, there are several of us here that do so. Just create a thread in "Need Toys" listing the ones you are looking for, also go ahead and post the ones that you have to trade (if you feel like it).
I could probably help you with a few. Unfortunately, from what I can tell, no one here has completed a base set (a set minus the Astro Mutants and/or exclusives) -- we are all missing the same 6-12 figures.
My observation is that the line has been killed off in the US. Though who knows. With the figures that seem to have not appeared in the US waves now hitting Canada, hopefully we can at least get a few sets complete through trades or ebay. Also, I think there is a slight possibility that MM could turn up at a US discount store (if it is indeed over and done at TRU). I have found Trash Pack at both Ross and Tuesday Morning in the past.
Above all, WELCOME!
Edited by steverotters, 07 March 2015 - 02:00 PM.