Yeah I forgot to mention that he collects some babies by putting a light on the side of the tank at night and the babes are attracted to the light. Then grows them out to keep the culture going. I made a larger setup to put on my 58 gallon seahorse grow out tank. So I'll see how it works.

Solid - do you know what species you have. From your description yours sound like the little ones I have in several tanks (I don't know the species). Really fast suckers that run around in figure 8's.The bahia mysids tend to stay out in the open on the bottom of the tank. I put 500 in a 58 with 2 seahorses thinking that it would take a long time for the horses to hunt them down. They ate them all in a day! That was an expensive treat.

I order them from Cheasapeake Cultures since they are a little cheaper. 200 for $50 or 500 for $100. They also have amphipods at the same pricing.
http://www.c-cultures.com/