A sporting goods store called Trails End, which used to be (still is?) affiliated with Bass Pro Shops, is having its annual "garage sale" this weekend. They have a lot of fishing stuff, but also an assortment of rifles commonly stocked. I think they accept used items from people and then sell them in the back room, which is why they call this their "garage sale." The owner typically has a couple of tables of handguns for sale at this event. It's the only time he sells handguns. Prices are usually typical gun show type prices -- not too good but not too bad either. Neither the store nor its selection of gun items is huge, but I still try to swing through there at least once a year. Location is in Fridley, on Central Avenue (Hwy 65) and about 79th, just north of the Friendly Fridley Chevrolet dealer. (This is all located about 3 miles north of I-694, on Hwy 65.) The sale runs Friday through Sunday. Depending on where your kid's conference is, this may be worth your time. (If you like motorcycles, etc., there's a Hitching Post just behind the Trails End where you could burn up some time as well.) Bill's North in Circle Pines is on the north side of the cities (about ten miles NW of Fridley) so if you're spending your time on the north side, you'd be in the general area.
By the way, if you're going to be on the southwest side of town, I've heard stopping by that newly opened Gander Mountain might be worth the trip. Their prices are typical GM, but the place is so huge that it's worth it just to bum around the store.