get dibond/alumacor/etc. in varying finishes. has a black core color, that is easily engraved by a router.
engrave the numbers, route the shapes and BAM... your signs are finished when they come off the router table.
...heck, even give them a clear-coat if you like.
otherwise, i'd just route .090 aluminum plate and apply digitally printed graphics.
....and a lotta work? hardly. 322 signs is nothing. should be fun, if anything, counting the $$$ you're making on each one should be a BLAST!