Buy an early SS or alphanumeric, they are usually a bit cheaper and all the parts are just about the same except for the boards. Learn to work on them and repair them as Nexyss said. Find a good example that needs some work, a "players" version. Then, down the road, when you know more about what's involved and the time it takes you can make a better decision about your TAF.
Get to know the local pinheads in your area, sometime you can get a good deal from a new friend who needs the space. You don't always need money either, Pins are like any other hobby and sometimes people loose intrest, maybe you have something of value or a service you could barter to offset some of the cost.
Lately I've been getting into EM's. Not as fancy as a modern SS pin, but just as fun to work on (if not more) and you can usually pick up a really nice one for around $500.
Good luck on your pinball adventure! Welcome to the club.