I would recommend doing some research on them at
www.seahorse.org as well before buying any. I remember one guy who was on here a while back that started with about 50 or so in a 5 gallon tank with a refugium. They were eating fine and having babies in the tank and the babies were surviving as well. Then, everything started to go downhill pretty quickly and I believe he may have ended up losing all of them.
My understanding is the feeding is the hardest part as the dwarfs do not readily "hunt" as some of the other species do and the food basically has to come to them instead of them chasing it. I think chasing it may burn up too much of their energy which they cannot really afford to waste being so small.
I wish you the best with whatever direction you decide to go.