I would like to keep the cost below $200 if possible. I would prefer something automated and server based that works with most of the common payment processors and sites like JVZoo, FSO, DigiResults, etc.
I've looked at several already such as IonCube, ZEND and CodeLock. IonCube and ZEND are expensive from what I can tell. CodeLock looks good but I went on their site ready to buy and for CodeTracker v 2.7 it said currently unavailable due to being in beta with no indication of when it will be released for sale.
I plan to start selling my plugin by the end of March 2013, so I have to move on this soon.