Around here, the S&W 2nd & 3rd generation guns sell for more than that, unless they are in really bad shape. $300 with magazines and a holster seems like a very fair price, especially if it's not in bad condition. Are you buying it from an individual or a gun shop? Any idea of round count, etc?
The SD9VE is a good, basic pistol, and they are current production...I bought one a little while back for $299 at Academy Sports. I'd buy the 910 since you don't come across those very often at that price, and then get a SD9VE later if you wanted one.
One thing the SD9VE does have going for it, or a couple of things, is that if you buy it new, you'll have a warranty, plus it is easier to field strip than a 910...not that a 910 is hard for basic field strip, but if you want to get the firing pin out and clean out the channel often, which I like to do, it's easier on the SD9. On the other hand, some people never do that, so it's not a major deal.
As for a Taurus...no way, no how. I've had bad luck with their products. Poor quality, poor service, and no trade/resale value.