WordPress membership site?

Hi, i already posted this but i think without being specific enough. What i am looking for is a wordpress membership plugin (or other) that will allow users to have a FREE account on my website. I would like one that has a lot of nice features for the members. I am certainly not looking to get this free but not over $200 for unlimited licence.

Another user on www.remarpro.com mentioned S2member?

Ohh and wanted one that can be applied to my existing wordpress theme, thanks a lot.