Then you're screwed as even the new Colt .22s are GSG if I'm not mistaken. You can get the Browning 1911-22A1 for closer to $500, but it's not a full scale 1911 in size and has dinky sights.
Do you have a standard 1911 all ready? If so, get a conversion kit. If not, why a 1911 in .22?