Buy or build an experimental. If you do, you can do any and all of the maintenance yourself. If you're not comfortable doing it yourself, or want someone to check your work (it's a good idea), you can call an A&P or one of your local EAA tech counselors if you're an EAA member. Even on a non-experimental you can do your own routine maintenance like oil changes, tires, brakes, that sort of thing. Of course it's a good idea to have someone show you how to do it right, but you don't need a signoff. For everything else you can do the work under the supervision of an A&P, if you have one you can call who will work with you.