Thanks for all the advices. I'm starting to think i should bite the bullet and shop at Keh's.
I don't think i'm going to go for the A16 but i was thinking that maybe i could get some A24 (much cheaper) and use them with 120 film (you're supposed to loose a frame but it should work, as far as i have read. Loose a frame but pay half the price, that's a lot of film to make up for it).
My ultimate goal is to have 3 backs that i could develop N-1, N, N+1.

Any thoughts - advice?