Glaock29: I'm not so sure about the $650 or less, unless you can latch onto a new or used Delta Elite for that price but, if you already have a 1911, why don't you see if you can find a complete 'upper' conversion for it. I see them at guns shows - complete slide, barrel etc. All you would need to do is fit an ejector (and the slide, of course) and that would get you a 10mm for less than your looking price.
Also, if you have a 1911 in 45, you can convert to the 400 CorBon or other similar wildcats - barrels are available. Other than those suggestions, I'm all outta ear wax. HTH. Mikey.