A friend of JTT sent me a note about the Graith USA Specialist Belt as a solid option for AIWB carry. The Specialist Belt has a very minimalist brass buckle with a gun-metal finish that stays out of the way of your holster. The buckle also allows for very fine adjustment coupled with with the hook and loop secured end.
The belt also has that stiff-but-not-too-stiff structure that works well for AIWB carry. The 1.5″ wide belt is constructed from a layer of scuba webbing wrapped with mil-spec webbing and is available in a wide variety of sizes and colors.