Welcome to the board, shrimp! I've had a coral banded shrimp in the past in my 45g and have found them quite preditory but very beautiful shrimp. One ate my cleaner shrimp($30) and he consantly harrassed my smaller fish. So, i would suggest not getting one, but others on this board have had luck with them. As they get bigger they tend to look for bigger things to eat and some choose other tankmates. If you really want one, you may want to choose a small one to avoid some potentional problems in the future. What size tank do you have and what are the inhabitents?
As far as where to find one, this site along with many others offer them but you will pay a heafty shipping cost. Have you checked all of your local fish stores? They are usually available. HTH