I have 2 Colt/Walther 1911-22s. They are excellent guns. Because 22 Long Riifle doesnt have the energy to power back a full steel slide, the makers of these 22 1911 guns have to use different materials to make the guns function. Some use Aluminum, some use Zamac(Zamak). The Kimber and Browning use Aluminum, both are in the $600 range. The Colt, GSG/Sig & Chiappa, use Zamac. They are in the $400 range.
As far as inner workings, the Colt and GSG/Sig are the most popular, and neither follow the true 1911 inner working, exactly. This doesnt mean they are not good representations of the feel, and ergonomics of the 45 1911.
Im not a 1911 expert, but I believe the bottom dollar to get you into a good 1911 is in the $5-600 range. The Browning, and Kimber 1911 22s are in that same cost bracket.
Many people balk at paying the same price for a 22 pistol, as opposed to the cost of a centerfire pistol. Thats part of the reason why a .22 1911 doesnt cost as much as the centerfire versions. People wont buy them.