I agree with heuerfan, I'm kinda old school myself. I started with a 29, to a 75, to a 220, to a 150. Depending on where you see yourself going and where you're comfortable starting sometimes doing it with a regular tank you can upgrade easily if you buy the right equipment from the beginning.
To answer your other question, there's plenty of great used equipment on our marketplace to save you some money especially being new to the hobby.
I love to help newbies so when you're up and running I can probably give you some free frags.
Good luck, it's a great hobby!