I have to agree with previous comments.
I wouldn't recommend a .22LR for HD, but, it's is a great beginner pistol and you can always buy a centerfire handgun in the future.
I would look for a used Ruger MI-III. I have a MKI and MKII. They are great guns and can be had for well less than $300 in good condition. It's a gun that you will shoot a lot, a very good idea for HD training, and cheaply.
If you're looking to move up to a centerfire caliber for HD, a used S&W K-frame (Model 10 -19) is a great choice. Police trade-ins are still showing up and will run $150-$300. These revolvers are very reliable and an excellent choice for HD.
Another option, as stated by others, is the S&W Sigma line of semi-auto pistols. New with a rebate, they are a very good deal. Yes, the trigger is problematic in the length of the DA pull and the weight. I have a .40SW VE I use for HD. 15 rounds of .40SW in a dead reliable platform. I have run well over a 1,000 rounds through my Sigma, and, while I don't like the heavy trigger, it's never failed me. The heavy trigger does offer confidence that you won't have an accidental discharge as might happen with a lighter tirgger. I chose the Sigma for the HD role over 1911's, Beretta 96, Glock, Sig, and many revolvers because of the reliability and trigger pull.
Matt