I will break a bit. It sounds like you're not exactly a shooter atm, which is fine--no ingrained bad habits.
First off, if the price tag alone is what keeps you from biting, don't worry about it. $700 is really not a huge bill in gun terms.
The other thing is--you're not CHP yet. The S&W DA/SAs are very nice guns, but they're not what I would call beginner-friendly to shoot. You'll have plenty of time to become proficient with one later.
I would suggest that you could use a good trainer handgun. You need something accurate--no point in practicing if there's no feedback. It should also have large, easy-to-use sights, and at least a passable trigger. As a final requirement, ammunition should be cheap and easy to get. 50 rounds of garbage S&B .40S&W costs $15 on Midway. For a measly $19, you can have 325 rounds of Federal AutoMatch Target.
So I would suggest:
--An entry-level .22LR target pistol, such as the Ruger Mk III or IV, Browning Buckmark, or S&W Victory
--A good .22LR revolver. Any S&W with a 4-6" barrel will do you well.
--If you must have a centerfire, the Springfield Armory Range Officer 1911 in 9mm is accurate and cheap to shoot. Beginner centerfire Bullseye shooters frequently turn to the RO as an entry-level gun, and shoot them, unmodified, at 25 and 50 yards.
A .22 target pistol--a very good one--will set you back around $400. The revolver, who knows, I don't keep up to date on the pricing there. The Range Officer should go for around what you were considering spending on the S&W.
Of all three, I would select the .22 pistol. Probably the Ruger, although you should pick whichever feels best in your hands. They're supremely accurate, all of them. I would be surprised to find a Ruger, Browning, or S&W Victory that couldn't shoot a quarter-sized group at 50 feet.
People who are good shots...it doesn't matter what handgun you put in their hands. The fundamentals don't change. They can pick something up, having never seen it before, and be proficient in the space of a magazine. And most of them, most of all of us, started on a .22.
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The other thing is, well...no offense, but I'd maybe be more concerned with other things than proficiency with the duty firearm. Passing the physicals, the written test, that sort of thing. Ability to understand, say, search law and what constitutes probable cause is a heck of a lot more useful than shooting ability. It ain't all action, it's a lot of think-work and hauling sullen, dreary, violent jerks, and a bit of cleaning drunk-sick out of the backseat. They don't show that part on Cops, where the drunk guy the audience was laughing at pukes all over the backseat and himself, and screams and spits for the 15 minute ride to his overnight accommodations.
Most cops go 30 years without shooting anybody. It's pretty much the second-to-last thing a department wants to see (the last being a dead cop). So when the guy that does your evaluations hears about you wanting to buy the duty gun and practice with it beforehand--can you see how that might raise a red flag or two? And it's not like there's a shortage of applicants...
But hey--that probably ain't you. Point is, I know a helluva lot of "professional firearms instructors" (don't make me laugh, fellers), security guards, and armored car drivers pulling down a whole $15/hr who applied to be cops at one time or another. And frankly, a few of them, I wouldn't give a damn BB gun to.
Best divorce the shooting aspect from the police deal altogether. Shooting's worth taking up on its own. And remember--probably half the guys in your class will have never fired a gun before, either, so you won't be in bad company.
Just sayin'.
