This piece is with warranty and for those who are misinformed custom firmware can be replaced by the original firmware by a software know as timemachine coded by dark alex. Thus full warranty can be availed even though it is modded.]
This is almost correct. However, you do not need Time Machine to go back to Sony Firmware.
But you still need the Pandora battery for using Time Machine. Does your friend have one? Is he selling it too?
You don't need TM to go back, therefore no point of having a Pandora.
and most probably, even if u revert back to original firmware, it is possible to know that CF was installed
Nope. It's very difficult, and requires reading the IDStorage keys, to check if they are corrupted [even this can be fixed] and it's not something I expect the "technicians" here to know anyway.
Irrespective of all that, your price is still too high. Just installing CFW does not increase the value of your PSP. It's not even the latest CFW, and in fact, there are some memory stick issues with the one you have installed.
Consider a further price drop.
