Outsourcing the one-off job would probably cost at least $50/piece.
Then again, You might be OK with that even if I'm not.
Enclosed ones are a bit tricky, but as soon as You finish making the auger, you can make a few dozen if You like.
Clover leafs are easy. Just pop the rivet and/or heat the joint enough to loosen the brazing and You can replace the original with whatever shape of leaf you want (/can make
If it's just an engraving You want, then the jewellers shop or a sign shop are your best bets.
Old manually operated GravoGraphs are plentiful (at least over here), so one master would be all that You'd need to engrave as many as you need as well.
Since no-one believes that the enclosed ones are pretty easy to make, here's a couple of new pics of an old job:
A hastily made Firebird button that has been left unfinished for about 20 years now...
I vividly remember thinking that I'll just quickly see if it'll work and then get it plated...
The auger is "stashed somewhere safe" but I'll be damned if I knew where.
Takes only about an hour to grind and heat treat a new one by hand though, so no great loss should I need one in the future.