Comment by bruckie

You could get that for $75 to $150 (depending on lead time and whether you want 5052 or 6061) from SendCutSend or OshCut (both US-based), as long as you're willing to use 3/16 inch (4.7 mm) plate instead of 5 mm. They'll also bend it for you if you want.

But at a higher level you're right: availability of fabrication services in the U.S. is pretty poor, and most shops are optimized for a few larger orders, not small mix orders like yours.