The other day i was looking for a way to encode my php scripts, in my search, i found three choices:

1. Zend Guard™ is available for $995 USD as a yearly subscription license.

2. Ioncube PHP Encoder: Starts at $199 USD

3. SourceCop : $30 USD

4. SourceGuardian™ : $250 USD

5. Turck MMCache: FREE [url=http://turck-mmcache.sourceforge.net/index_old.html][download at sourceforge][/url]

Ofcourse, you pay for what you get. If I could afford it, I would go with Zend.