Thanks everyone. I'm now convinced to go ahead and try using one of my older Singers for the job. The cushions are a simple, square shape, so it shouldn't be too difficult. I'm looking into purchasing a teflon foot, or possibly just using my walking foot to help the machine sew smoothly and evenly. The leather is insanely expensive, so I don't want to screw this up.
That being said, a new couch is probably 3-4 times as much, so I guess that I'm, "saving money."
~ C