Matt- Go for it! I'd recommend finding a cheap 6x6, either folder or TLR. You can often find an Agfa/Ansco for around $25US. A TLR can be had for more, but the important thing is to get started. If you like the results, you can upgrade as funds become available. Until then, you can hone your processing/printing skills. The limited number of exposures per roll will help sharpen your compositional skills.
Then, in 2013, you can ask about 4x5. And, in 2014.... :-)