there are videos on youtube on where you can get over 170 themes!
here is a pretty good link with a shit load of themes!
105 themes to be exact but some are for M33 users (i recomend you go to a M33 firmware. check out my guide on the psp general section on how to create a pandora's battery without acustom firmware psp form psp with 1.50 kernel!
(its in my sig)