Firefly and River Tam fans can buy their own goodies, just like "The Cape" fans have the possibility to bid for "The Cape" stuff (see "The Cape Auctions") but ; i have listed a few examples.
Vinyl artwork for the "River Tam and the Fireflies" album
The artist created a retro-looking illustration for a Serenity vinyl record. The music is fictive but the artwork on the album cover is really nice.
Joebot : "A few years ago I got into collecting Vinyl records with artwork on the front. I've never really had a chance to design an album cover, and when I started thinking about what would be a fun illustration to do for Serenity, I thought since music was such a strong component of the show, that an album would be perfect. I was always a fan of old vinyl art of children's music so I wanted to incorporate a retro feel. It is a known fact that River Tam is a badass, but for now things have taken a lighter direction with "River Tam and the Fireflies".