Not sure where you live, but if you live in New England, Newbury Comics always has TONS of them. You might want to go to some shows. Bands almost always have them for sale, and they're generally much cheaper to get them directly from the band than to get them from a store.
It really depends on what kind of patches you want. I'm not sure exactly what you mean by models and names. You might want to try getting into silkscreening and/or stenciling and try stenciling your own patches onto some heavy material.
