Lease one and see if this is something you really want to get involved with. If you're ready to take the plunge and buy something, a new van is always best as far as reliability, but you can also find real bargains at rental companies. These companies are great about keeping their automobiles serviced like they should and keep great records of all maintenance done. If you do buy something or use your own van, don't even think about hitting the road without a AAA membership. You're going to need somewhere to crash.
Hotels can get expensive.
In other words, play your gig, drive to the next place you're going, check in, sleep, get up, play the next gig, and go back to the same room that night. Campgrounds like KOA are a reasonable option if you just want a shower and don't mind sleeping in a tent or the van. Another great option is staying with other bands you meet along the way or ahead of time. People love to help other people. Take advantage of the Internet to meet people and work on your relationship ahead of your tour.