I agree with those that said that shooting an air pistol is definitely good practice to build your shooting fundamentals. Like anything else, I am a believer in buying good stuff, or at least decent stuff. I have a Beeman P1 airgun. The grip frame is the same as a 1911 and can use 1911 grips. I also own a Baikal IZH 46M which is a very accurate handgun. Finally I bought a cheap BB pistol that mimics a Walther PPK. It isn't very accurate and the trigger is always on "double action", but it is fun because it is semi-auto.
I am giving serious thought to investing in a good Airsoft gun. I don't know much about Airsoft so some of what I am going to say is my take on the subject. The thing that Airsoft seems to have on pellet and BB guns is that the Airsoft guns appear to be the real thing. Other than weight, they handle just like the real thing. I am thinking about an AR15 airsoft gun. From what I have seen, these guns are very close to a real AR. They have flat top recievers, rail systems etc. So, you can mount real AR accessories on them, making a training tool very similar to your main "go-to" carbine. You can add an Aimpoint, you can add a tac light, you can use a vertical foregrip, you can add a tac sling, etc. It seems to me that you can greatly enhance what used to be your dry practice. I believe you can do mag changes etc. In addition, you can set up your own shoot houses, just like the ones at the big name shooting schools. You get together with one of your friends and place targets in various parts of the house. With one person not knowing the target positions, you can then give them a senario and have them clear the house, rescue the hostages, or whatever. You don't need a special shoot house, you can use your own houses, yards, garages, or whatever. Then of course you can increase the realism by using the Airsoft guns for force on force training. If you maintain a serious, mature attitude, you can gain valuable insight.
Buying an Airsoft handgun that is a clone of your primary defense handgun would provide the same benefits. It would seem that you can use your regular holster etc.
I am not looking for an extreme tackdriver for target shooting. I am looking for something to use for at home tactical training.