I've only just thought of selling my GP2X F100, and now I see this.
Basically ever since I got it it's had a dodgy joystick, it seems the spring inside it is broken, so as you push down to select things normally, it is doing this all the time when you don't want it it. Even if you just move it sideways it will quite often select stuff. I've found that I can pull up the joystick with the ends of my fingers and move it about like that to stop it selecting things unwillingly.
Because of this I haven't used it in months, but last night I got it out and tried to fix it. I took it completely apart and found it actually looks quite hard to fix. The joystick unit is soldered with about eight pins to the board, and it looks like you can't open the unit without unsoldering 2 of the pins. (It is a round unit, with a piece of metal as the top, on two sides the metal folds down where they are soldered to the board. I was thinking of peeling back that metal top so i could get a look inside, but two seperate things are soldered through the board, I'd have to heat both those individual connections to get the metal off, that looked hard. So i gave it a little go and didn't get anywhere (I'm not experienced at electronics at all so it's quite possible that someone else could do it quite easily.)
So in the end I just put it back together again (This morning). I seems I didn't put it back together quite properly as there are a few gaps, but one could very easily unscrew the thing and put it back together properly.
However it is fully functioning, apart from off course it selecting things when I don't want it to.
Also, the actual joystick cap is missing, so it's just a stick of metal, but you can buy joystick caps for a couple of quid I think.
So basically I can't fix it, but probably someone else can, or it might just be easier to somehow get a new joystick unit, but it would still be a soldering job.
I think it's got a couple of scratches on the screen, but barely noticeable, and I've got he original box in good condition.
So if you (or anyone) wants it and thinks they can fix it, or wants it for parts, make me an offer- I don't know how much to ask for it, although I did originally pay about £60 for it in almost the same state as it is in now...