With some modifications, you can use an arbor press as a snap or grommet press. If you're handy enough to drill some holes in the arbor press to fit the snap dies, then all you would then need to purchase would be the press dies.
You can see full photo album here, but essentially you would need to:
1) drill a hole in the plate (that's the little disc thing-a-ma-jig that sits at the bottom of the arbor press) to fit the bottom (ie. cap) die for the snaps.
2) drill a hole in the bottom of the rack (which is the long vertical bar) to fit the top (ie. socket or stud) die for the snaps.
3) install a pin in the side of the rack that can be tightened to hold the top die in place. And voila! you've got yourself a home-made snap press!