Need 50? or just a few?
You could contact Metal Supermarkets...they've got all sorts of stuff and the chop-saw equipment to cut it to size.
You pay by foot...but with so many cuts you might have to pay extra. Alum is quick to cut through...but you'll still need to clean up the edges and do finish work.
I'd call Dave (Imperial Engravers)...and have it lasered in.
If you're looking for thin stock...they have brass/alum on hand...but don't know about the dimensions you want. They do have material to do plaques on hand....so maybe that'd work.
Dave's a good guy.....though double check the spelling first!