Some people really like the idea of a 1911 with a .22 conversion on it. Personally, I don't think it's all it's cooked up to be. $400 is much more than you need to spend to get a nice .22 semi-automatic. The Ruger Mark II/III series are terrific pistols that will last lifetimes and you should look for a used one for a little more than half of that $400 you quote.
Also, FWIW, the Para-Ordnance isn't one of the lowball budget 1911 makers. You may be thinking of Auto-Ordnance, which surely is. On this subject, spend a little more when you are ready to buy a 1911 style .45 automatic and you'll likely end up happier.
If you want to enjoy yourself and have fun at the range, the .22 pistol is a supreme tool for exactly that. If you want to become a better shooter with a lot of trigger time, the Ruger Mark II/III is excellent in that role. If you want to shoot a lot of ammo for very little money by going .22, I would completely and entirely agree with a nice rimfire semi-auto like the Ruger.
However, please don't kid yourself in to thinking that you can install a .22 conversion on to a 1911 .45 and shoot all day with it and you'll be proficient with your .45 because of it. Just won't work that way. You will be more familiar with the grip and trigger and the slide release and magazine release, and that's all. The recoil, working the slide, clearing a malfunction, and even the sights will be dramatically different.
If you want to be practiced and proficient with your .45, you need to shoot .45.
You will be happy with a good used Ruger Mark II.