Also, gas / diesel engine, standard shift / automatic, long / short body preferences? Think about what you need vs what you want and find the balance. What do you already know about busses / mechanics / carpentry, etc., and what do you feel you can learn to do? The answers will go a long way in determining what you should look for.
Remember also that there are lots of knowledgeable folks here who will help in every way they can. Don't be afraid to ask questions, the only stupid one will be the one you DIDN'T ask!
Good luck and keep us posted!