Seahorses aren't the best for newbies......you'll probably need a constant supply of LIVE food.....wild ponies won't eat dead food very often. They have no stomach (literally), and food goes right through them....a constant supply of live brine is a good idea. I am only assuming you guys are new by previous posts, so if you already know.....sorry. If not......low water movement, something for them to hang on, live food, NO fish other than mandarins or pipefish really, and seahorses are very sensitive to osmotic changes....I take about five hours to introduce them slowly to their new water. Seahorses are one of the most delicate creatures I have ever kept, and I doubt I would spend much on them due to their dismal survival rate.
I know you didn't ask......just throwing out my experiences with seahorses. Tough to keep really.