Go to the design center at Lowes, Home Depot, Mennards etc. Take your dimensions, color pallete and budget. Choose from wood, metal, glass, granite, corian, you name it. The same skills that go into kitchen cabinetry will cross over to your audio rack system needs. You can plan your storage and airflow needs as well as lighting and electrical all at the same time. You will save much over a dedicated audio custom piece, and it will add to your homes appeal. As a bonus everything will match.
(p.s.) there is a lot of wiggle room in their pricing for cabinets and lighting.