I've definitely noticed a downwards trend in term of availability over the last several years. I think a lot of it has to do with people specializing in one kind of arachnid. Some people keep purely tarantulas, while others keep purely scorpions. Not a lot of crossover in interest, which is unfortunate, as they are both beautiful animals(I myself keep both, and other animals). Tarantulas are the big ticket item right now so you will see a lot more availability and captive breeding going on. Give it a few years though and I'm sure you'll see more scorps come back on the market. With beautiful species like Rhopalurus junceus and Tityus asthenes on the market scorpions as a whole are bound to see a resurgence in popularity.