I've had stamps made by both Buckeye Engraving and Infinity Stamps.
With Buckeye, you have to call them to get anything done. You have to call to get updates after the estimated time for completion is over. In my case, I had to open up a dispute with paypal to get them to ship my stamps and respond to my emails. Otherwise, the stamps are fine quality for around a hundred bucks a piece.
Infinity Stamps is an absolute pleasure to deal with. They are great communicators, quick to respond to emails, always pick up the phone when called. The worry free service, however, will cost you about twice as much as Buckeye. Still, top quality product though...
A&M Steel Stamps is also highly recommended in the community, but I have not yet ordered anything from them.