Saying your not sure on budget leaves it abit wide open! Like it's been said before if you want to ride downhill at trail centres, you would be miles better on a alpine/freeride bike. For trail centres I have an Orange 5, because I got it from work. But for proper downhill, where there is a proper uplift, to take you to the top and no pedaling up hill. I have a Orange 224. Either way there both expensive bikes. A good seconde hand Orange five will set you back about £1500- £2000. And a Decent Orange 224 will be around £2000-£3000 seconde hand aswel. You can get cheaper downhill bikes, but to be honest you will be looking at around £1000 for a half decent bike.