Price wise, widebars (pulcher) and NGT's would probably be the most expensive and silvers being the cheapest. They also grow slowly, so large dats will be quite a bit more expensive than small ones. Silvers also do best with some salt in the water. Brackish is recommended for them, although they can live in full fresh, but in my experience are more disease prone that way. Hope that helps. I'm no expert though. I'm sure someone who has kept more of the different types (I've only kept silvers and thin bars) can help more.
