I'm looking to buy a camera/lens combination to take photos of my hobby, which is salsa dancing!

It seems like taking good photographs of salsa will be difficult. It is inside, mostly dark, and people are moving fairly fast!

In light of this what camera and lens would you recommend, and how much will it cost me? If possible can you give me two scenarios.

The first is that money is not an issue, and I want to get the best possible camera and lens for these challenging conditions.

The second is if I would like to get the best bargain, while still getting a system that can cope with these conditions. This might involve buying a lower spec camera and lens, buying a lower spec camera and high spec lens, or vice versa. I'm also open to the idea of picking up items second hand...

I'm pretty green around the gills at photography, so the less jargon used the better!