Back in the early 2000s, I did find one merchandise website that sold t-shirts, baseball caps, and coffee mugs that read BBF on the front, and on the back "Belly Button Fetish". And there was also IBBF and OBBF, for "Innie Belly Button Fetish" and "Outie Belly Button Fetish". I haven't found the site since.
But yeah, of course I would buy bellybutton fetish merchandise. If Clips4Sale sold their navel play clips in DVD instead of solo clips, I would buy them. And as for female celebrity bellybutton molds, I would pay top dollar for an AnnaLynne McCord or Julia Voth mold. It's a totally untapped market!
Credits, MikeBrooklyn.