build it yourself? It might be a bit over you budget at the end of the day, but you could potentially spread out the purchases across six months.
I just spent the past hour researching the 2011 pistol. It's available in 80% form and completion is much like completing a 1911, but you get double-stack capacities. Also the magazines cost $75 apiece for I'm really not sure what reason.
But 6.25" threaded 1911 barrels are out there. Possible available in 10mm too but right at the moment all I can find is a few .45's on Ebay.
No, wait …
https www.fusionfirearms.com/1911-government-barrels
Know nothing about the company, but they have 5" threaded 10mm barrels.