IME, rainbows are pretty epensive if you get the good ones. At the lfs I work at, the sheapest rainbow we've ever had, is 5.99, for dwarf preacox. The larger species:yellow, turquoise, red irian, bosmani, splended, red tail, etc, are 8.99 for the small ones (1-2 inches in length), 18.99 for large ones (2-4 inches in length), and 28.99 for extra large (anything larger than 4 inches in length)
So they are expensive, but are worth it. We keep all of out rainbows in a heavily planted, with vals, wisteria, and crypts, 55 gallon. I love the tank, the rainbows are always swimming, and when you approach the tank, even if it's to catch them, they swim right up to the glass to greet you, then swim away as soon as the net enters the water
I highly suggest doing a rainbow tank, but if you do, there is one thing that you MUST to. Plant it.
