Its about 45 seconds down the road from the main gate as you head towards 192. As someone mentioned, just opened up a little over a year ago I think. And thankfully they have a light so you can turn left back onto Old Wilson to get back to WH.
The Walmart is on the property behind the Black Angus restaurant. That land used to be occupied by a large EconoLodge that connected to the building the restaurant is in. We actually stayed there several times years ago. The hotel was destroyed by a huge fire a number of years ago.