It's a great gun and you got the best deal I've seen. The 5946 is probably my favorite S&W 3rd gen, but it's true that they are slightly overlooked. I say 'slightly' because they do tend to bring about $50-75 more than the identical 4046 because of caliber(or perhaps just because the 4046 is the more common police trade today). Most people prefer the TDA and most people prefer a lighter gun, but in certain situations I don't believe there's a better pistol than the 5946(CCW would not be one of those situations, but in a permanent installation,.....like HD or a vehicle firearm it can't be beat).
I've been sucking up every 3rd gen DAO I can find for the last three years(finances permitting). I check the GB auctions several times a day for updates, and the 5946 specifically has been selling for $400 and up when shipping and transfer($20 each in my case)is included. A hammer price of $350 is uncommonly low,.......they've been relatively hard to find at anything closing below $400. I just picked up another this week minutes after it was listed. Had an opening bid at $275 with a BuyNow at $300 and I jumped on it. Very nice looking gun,.........without the BN I'm sure it would have topped $400 easily.
These are the prices I have tracked online for the last several years totaling several hundred sales(I think I've bought 8 or 9). I hear about people finding better deals locally like yours and others posted above, but the market for an all stainless DAO is pretty small when it's restricted to the LGS and the people who walk in the door. If the gun fits your need, it's a good one.