Jesus, you could get a smelter, forms, and sand for far less than that. and do it yourself. WTF?
you might look into a machine shop, or a fab shop instead of someone to do a casting. all you're really looking for is a tab on a cylinder. a cylinder of Ali of the right outer diameter with some flat stock welded on of the proper length. Really a simple set up. it'd be stronger if it was milled from 1 peice, but that probably wouldn't be cost effective.
Say you bought a tig set up for Ali ($1400), a cold saw for the cutting the stock($300). Drill press ($150) and good metal bits($100). you're still under $2000 in tools and probably materials for your first 50 or so units.
Set up a jig and do production runs for your cuts and you can blast out 50+ in half a day. if you sell fifty at $25 you're at $1250 so two runs of 50 and you're in the profit range. three and you're well into it. $25 is more than enough to cover the cost of the materials and the time and consumables used for each unit. It's all about getting a production line set up.