My recommendation is get a 5-6 inch Full suspension bike, and get a second cheapo bike for riding to school. You can get into the full suspension market for around 750.00 for a decent bike but should be looking closer to the 1200-2500(brand new) range. I suggest keeping an eye out on craigslists. Especially now that bike season is starting to wind down. Some upper end bikes go for a good price. Also pay attention to the area you plan on moving to and ask what kind of trails they have. My suggestion is to reask this questions on mtbr.com
http://mtbr.com/