Save your money brother - and I say that from having bought into the hype and got Crimson Trace grips for my Sig P-229 back in the day.
I bought into the sales pitch hook, line and sinker. I forget what I spent on those things, but it was a couple of hundred easy back in the 90's.
I used to dry fire practice all over the house with that thing when I first got them. In that aspect, it was cool, but it didn't tell me a damn thing about how well I was actually shooting ( more on that in a minute ).
After about, maybe 6 months, I noticed that the red dot had become more of a red splash, it was well over the size of a quarter. So, I contacted Crimson Trace, sent them back and they sent me a new pair. Apparently the glass they used at the time, would be affected by the hi density light of the "laser".
Okay, fair enough - the new one worked well and I carried it that way for a couple of years.
So, I am at the range one day with a good friend, a much older guy who had done a TON of shooting his day and he says to me "You know that damn hi tech toy points TWO ways don't you?"
See, there in lies the problem. A bad guy will be able to see, not only where you are, but also what angle you are firing from. Anyone with any training is going to be able to assess the situation and find cover based on that information in a PDQ motion when their life is on the line. Then you are hung out to dry as they know right where you are and can start shooting back.
My vote would be save your money.
However, for good dry fire practice with a "laser" that will actually benefit you:
Rovatec Bullite Training System
Here's a good review
by the guys over on m4carbine.net ( with thanks from Firearm'sTalk ).