Since no one's willing to touch your thread...
Everyone has an opinion. whether or not it works, one can say it will, one will say in won't. I was told by a highly revered LFS owner my 210 would be too small for a carpet. (I think he thought I was new, I was asking him alot of questions to see his points of view). I now have 2 happy carpets in a 75. I don't know you or your abilities and dedication, just like the "know it alls" don't know mine. I think the average person asking for a carpet in a 55 gallon up for 8 months is asking for trouble, but you may be above average and pull it off with ease. I did alot of research and reading before I got mine. You'll find after all that work, there's still more you don't know. No one knows all...
As for price, you can spend $30-40 for a small from a LFS, or hundreds$$$ and up on line. I've found it's best to have the LFS order one and GET IT BEFORE THEY PUT IT IN THIER TANKS!!! Or live aquaria - they stand behind them with a guarentee. LFS do not. As for how to choose a good one, that's a thread of it's own. Good luck.