Found it at an Autozone this evening, so it set me back $4.99. However, given its popularity and that it was a major want, I figured that it was worth the extra price. Who knows if I'll ever see another one on the pegs?
Thanks everyone! That Autozone is the only place I've seen any of the Off-Road vehicles thus far, and the only other one on the pegs was the Baja Bug. They also had one of the vintage stock cars - a '56 Merc - which was my first sighting of any car in that series.
Here's a few photos of the Silverado out of its package: