Is this feasible?

I've thinking about doing an experiment that will (Hopefully) show speciation in something, currently I'm going with Acheta domesticus (The common house cricket, I'm thinking I'll obtain them from a bait shop) but if anyone has suggestions for a subject that's easier to keep/has a shorter lifespan or a shorter reproductive period then by all means tell me. My basic idea is to try and select two groups for conflicting traits (I.E., resistance/weakness to an anesthetic (might not be feasible), resistance to alternately heat/cold and perhaps coloration) the ultimate goal would be to create a group that is infertile to the original and the other group but fertile within it's own group within a short amount of time. What would be the proper number of generations for such an experiment? Does anyone have any suggestions?

over 9000

Most folks doing this sort of work like to use drosophila melanogaster, for the reasons you just said.

Hmmm, you're right, they would be better. I wonder where I can order some...

Did you try Google search for "biological supply"?

Alternative:  Leave a piece of fruit on the counter overnight.
Next morning, collect drosophilae.

It's not like flies are a rare commodity that is hard to find.