After you have you PPL, a share can still save you a bundle. I bought a 1/12 share in a C150 to get me up the 150 hr mark. I flew 100 fun filled hours for about £45/hr (that's the average incl maintainance, subs etc). It has it's pit fulls (like having to shell out if something needs fixing....and it invariably does). But I still saved a bundle compared to renting or even going to the states.
As, it happens I'm now looking to sell my share (shameless plug). PM me if you want more info.