Did you mean expensive BRASS or expensive AMMO?? Most 10mm ammo is watered down crap, and is barely faster than 40 Short & Weak ammo. The original spec for 10mm is a 200 grain bullet at 1200 FPS
, and for the Short & Weak it's a 180 grain bullet at 980 FPS. The cheap 10mm crap is a 180 grain slug at 1030 FPS.
WHOPEEEEEEE The brass itself doesn't cost that much more than 40 S&W, which is why I asked the question. If you handload, this is one of THE calibers where you can save a ton of money. If you don't handload, there are about 3 manufacturers that put out REAL 10mm ammo, and it is on the spendy side.
Finally, the whole concept of buying your FIRST 1911 in 10mm rather than 45 seems a bit odd, and if you have several other 45's then it's probably no big deal. If you don't have several other 45's that you have shot a lot, then it could be a bit of a rude awakening the first time you shoot some 200 grain Buffalo Bore ammo. And finally, if the trigger is on the lousy side, I'd take a pass regardless of the caliber, and with hot 10mm loads you REALLY don't want that thing recoiling on you when you're not ready for it.