You will definately not find a PSP wiht CFW on any store online or offline. I know it may not be the most economic effective to buy a PSP with custom firmware when you (already have a PSP and) can do the Custom Firmware installation yourself, but it is another option for people who may not want to risk, or do not wish to place CFW themselves on their own PSP.
So, without further delay, here is the link I found on eBay.com: Buy A PSP With Custom Firmware. Its good for the next 6 days or so. Thanks for the visit and have a nice day! :D