Personally I believe there is more supply than demand. Your typical carpet python are literally being given away these days. If they're not oddballs like albinos or hybrid patterned critters then they are out there in their droves.
Not everyone wants to keep a reptile, not everyone is able to keep them either (especially with threads like "make my mum let me keep a snake"). Sure, it's a growing hobby, but like the Aussie car industry, we don't have the population to keep up such a huge supply (IMHO).