ZaRDoZ has a basking tower constructed of bricks stacked 6 high.
They're heavy, stable, and there are 3 ways to stack them.
Patio/landscaping blocks
Blocks of dimension lumber would also work (2xs, 4xs...) Just seal them first, as they're usually softwood that may be toxic to beardies.
Sure, you could use something like those shelves; I guess it depends on whether aesthetics come into it, and your preferences.