So far as I know, only retro friends carries fm towns marty games, but nothing really to get excited about. Super potato has some peke and lots of MSX games too, but no towns stuff so far.
As for the liberty (nearest from potato just around the corner) i agree on his cheap prices here and there, but on the quality side, there isn't much for hardcore mint collectors.
also worth a look is champ retro games, even their prices are usually set higher than those from potato, but I had my lucky finds there as well. not great fan tho.
also good ol' media land still caries some retro stuff (FC, PCE, MD, SFC etc.), even the variety is very small, the prices are very good, if you can find your games of choice. f.e. they had a darc x w/o spine for below 3000 once.