I would get the firefish INSTEAD of the seahorses.
There are experienced aquarists that wouldn't touch seahorses with a ten foot pole.
Too much effort and too much time to dedicate, and pigmy ones are even more so.
... and to be honest, seahorses are boring. There was a display tank at the LFS and they pretty much did nothing but hang onto the plants. I was tempted myself by seahorses, so I spent some time staring at them trying to decide whether to take the plunge: They might as well been plastic ones.
Mind you, this is my experience and my opinion, you have to decide for yourself, but don't underestimate the effort you'll have to put in.