Shootall: Lynnie is correct. A new slide will run at $200, more for better. A good barrel is around $100, putting it all together so it works properly - priceless, if you do it yourself but it may run a couple of hundred to get everything fit properly together. Pricey possibly altogether.
I don't know of anyone who makes a Commander length 1911 in 10mm but full bore 10mm loads would recoil noticeably. Glock, Tangfolio, EAA, and others make 10mms in 5" but you would have to check their websites to see if they, or others, had other offerings
If you have already tried the 400 and found it lacking, there is one called the 40 Super (?) (Starline used to sell the brass). I think it is a longer bodied version of a necked down 45 case with a shorter neck than the 400 and may be able to use heavier bullets. I know that in the 10mm calibers, 180 - 200 gn slugs, even at moderate levels penetrate extensively. A bottle-necked case design allows for the reliable use of (very) flat nosed bullets (swc), enhancing the calibers' 'authorita', especially in the field....
Mikey.