Hey dude, well, i feel your pain, i used to be stuck with a "homebrewless" psp, and it really sucked, it sucked so much, that i went out and bought a second one so i could play homebrew. lol. with all the advances in psp hacking though, i now have 2 homebrew compatable psp, and thats what i call cool.
Anyway, there does exist a way to downgrade a 2.81 psp back to 1.50, and from there upgrade to a custom firmware (at least i would recomend doing so, cuz custom firmware is the shit!!! 3.03 OE C foeva!!!!!) anyway, you can downgrade as long as you have this one key element:
You need to have a copy of Grand Theaft Auto: Liberty city Stories, that is unpatched. i asume that as you dont know much about psps you wouldnt know about the exploitfound by hackers in that game's save options, that allows the execution of unsigned code, or, Homebrew.
So what your gonna want to do is get your hands on an unpatched copy of that game. how do you know if its unpatched?? simple; all you have to do, is insert the UMD, and wait for the psp to display the UMD game option, and the System Update option. the system update option is what you want to look at, because the version of the update is how you determine if it's patched or not. simply put, if the update verion, is 2.00, then the UMD is unpatched, if its 2.60, then it is patched.
so...
2.00 = Good
2.60 = Bad
So, if you can get your hands on this one item, and you have the confidence in the hackers who discover these things (they really really know what they're doing!!!!) then go to this link, and follow
all the instructions. if you can do so, then you will be going back to 1.50 in no time
http://www.psp-hacks.com/file/1034
the file comes with the instructions, but if you have any more questions or concerns, dont hesitate to reply back, myself, and any of the people on this forum would be glad to help out.
Good Luck Freind
Peace