ditto that i sold a ttr 100 a year ago it was really a 'wreck' i got 370 for it and the fellow sold it for £500 with out doing anything to it,
a derbi sender is not a mx bike its a wanna be enduro with a 50cc you need to have strong legs to push you up hills,
get a trials bike like x-dream says, cheaper to run, and last longer a lad i was talking to got an aprilla climber 240 for £200 running apart from the swing arm was snapped which he sleeved, the fork seels are shagged, and the disc pads are nacked and they are hard to find parts for and he thought it was a bargain, its best to spend at LEAST 800 on something that has all the stuff done, and you can parts for look for stuff like new tyres on them as they will save you 50-75 quid, and suspension bushes, i dont no what the situation is down there but getting a trials bike for under a £1000 up here is really hard :turned: dont know what mx bikes are like but imagine there is a few wrecks about for 600 that would fix up :)