Camping is first come first served. There is a campground, but you can just rent hammocks with mosquito nets at Jaguar Inn. Don't bother with cumbersome camping equipment, when a room in most other places costs little.
The best and cheapest way to get to Tikal on a budget is to take any of the overnight buses, deluxe or otherwise, and then hop the next second class bus, not shuttle,from that very bus station to Tikal. By the time you screw around and find a shuttle, you will pay a lot more (50Q vs 20Q) and for a cab or tuktuk without arriving there much later.
