The only breeder in the US who has them each year is Bob Clark, i think they are $375+ but im not too sure.
Aquariums are nice but they arent the best setup for a Dwarf Burm, Dwarfs are a very shy & nervous species who stress easily. The best setups for Males & Females would be a 3x2 Tub for an Adult Dwarf Male & a Adult Dwarf Female will thrive in a 4x2x1 (LxWxH) Vivarium closed in with one door. So if you decide to get a Female i suggest you invest in a BoaPhile.
Anything younger then an Adult will be happy living in a rack system or tub.
Daniel