if you have tools already then placing in a custom firmware takes 5 minutes. all psps are, at this point in time, hackable.
the only problem with the new psp slims is that there is no way to make a pandora batttery with it. but you can still hack the psp.
if you have a friend with the tools then placing a custom firmware on the psp should only cost the psp itself. psp plus 4gig memstick card is all you need to pay for. you should get the firmware installed for free. you shouldnt be paying for people to install it.
but tool battery will make it cost a little more.