The convenience store is located at the south east corner of Stassney and S 1st St. I think the store is painted yellow now but I'm pretty sure there is still an empty lot behind it where the van was parked. In the movie you can see the Walgreens across the street which is
still there. There are a few more shops (a tax place, a Chinese food place and a laundry mat) in the same lot as the convenience store where some of the action took place.
In the scene where they are walking down the street (Buff is talking about how he would blow his money if he were rich) was shot on E Oltorf somewhere between I35 and Willow Creek Dr. There is also a scene in a Whataburger which I believe is the one on E Oltorf.
The parking lot and grocery store they show before the group goes into the Chinese food place is at Mopac and William Cannon (I think). I don't really know if the actual Chinese food place is/was located here.
Also, during the opening credits there are drive by shots of shopping centers. At least one of those is on S 1st and Stassney (look for the comic book store in the shot).
At the end, there are a few shots (one of them you can see a "Color Tile" sign). Those shots were right around Ben White and Lamar.
Apparently Linklater likes to use deep south Austin for a lot of his locations. Lee High School in Dazed and Confused was Bedichek Middle School which is only about a mile south of the convenience store in SubUrbia. Also I'm pretty sure the scene with Alex Jones in A Scanner Darkly was shot in front of an old Short Stop Hamburger place which is catty corner from the convenience store in SubUrbia.