I have spent dozens of hours researching dwarf seahorses. Seahorse.org has an entire forum dedicated to jush the zostrae (DSH) species. After a ton of reasearch, I got a 2.5 G AGA, sponge filter, 25w heater, basic flor. light and natural seafans and got the whole thing cycled and ready for ponys. Then we decided to put the house up for sale. So, plans diverted.
A 2.5G is good for about 10 DSH. They are painfully tiny if you have never seen them in person. You will almost never find just 2 in that size tank. They will breed, as well. That is good, as their lifespan is only 1-2 years.
You will need to feed live, enriched baby brine shrimp 2-3 times a day and you will need to hatch at least every other day to keep the supply up. They will rarely if ever eat frozen mysis and adult brine are too large for them. This was the part I decided I couldn't do if a move was in the works. Some people have luck with copepods as a food source if you think you can raise those in large numbers.
As for getting them, there are a few really good places to order on the internet. I don't remember the specific sites but the seahorse.org folks have a ton of experience. You must go for captive bred. Especially if it is your first time with them. They will seek out food better and don't bring in the disease that WC specimens do. I have seen a few at AU in the past, but they wanted $90 for a pair.
I do have most of my setup if you are interested.