Hi! welcome to the forums fellow desert dweller!
There are a few shops areound here that sell seperate sliding lids that would work great for a corn if you have that kind of tank. Az Reptiles Center and Predators Reptiles are both good places to try. Corns, like beardies don't need the UVB because D3 is not as critical for them, so your new baby should be fine. What kind are you looking for? Between all of us out here, I'm sure you'll find just what you're looking for.