ahhh, I'm sorry..
Believe me I know what it is like spending a lot of money on prep materials. I have a stack (more like a mountain) of Examkrackers, Princeton Review, and Kaplan books at home.
Try ebay or Amazon sometimes sells used editions for really low prices. If you know anyone who can burn you copies of the Examkrackers Audio Osmosis that'll save you tons of money too (that's what I did).
But again, regardless of what prep system you choose, it is mostly dependent on your strive and hard work. Examkrackers is just really good for their practice material (some may argue it isn't that great, but again it's up to the person), so you could pick up the practice books (especially Verbal).
I find that books explaining concepts really don't differ too much from each other, other than the examples they use to illustrate a particular concept.
Good luck!