I could see them doing okay at a Dave and Busters if they have some fans old enough to remember them and still be nostalgically charged to try and win them. But I also see them being shoved near the sides and bottoms of crane machines in malls or grocery stores that have them for some reason.
But I think you nailed it. Fraggle Rock, unfortunately, isn't nearly as popular as The Muppet Show or Sesame Street characters. Or heck, even Labyrinth or Dark Crystal. The lack of good merchandise is directly correlated with the lack of interest as even in FR's heyday, it was on a premium cable channel. Sure, we had some great stuff during the great Muppet Merchandise resurgence of '03-'06 where Henson was actively trying to get FR out there as well as the more famous Muppets. FR plush with DVD's hit Target. Doesn't get more mainstream than that.