Engraving Bricks

I am working on a fund raising project for the Boothbay Railway Village.
We are looking at a brick walk, where people make a donation and get
their name engraved in a brick.

Ive found a couple sites on the web that do this, for $20 per brick.
Most seem to sandblast them, but one site claims to be 'real engraved'
with special machines.

Id guess a diamond bit in a router on a simple CNC table ought to do the
job. I think Id make the machine a disposable- maybe a wood or mdf
structure. If I got 100 to 200 bricks out of it before it died I would
be ahead of the $20 per brick. I only need a working area of one brick- 4x8"

Has anyone tried this? Any suggestions for a source of bits?

ron ginger