I built my own using 80/20 strutted aluminum and the wood of my choice. I liked it so much I built a second one for my wife. Check out my avatar picture and see my profile pictures for more ideas. The nice thing about DIY is you can design it the way you want and can modify it in the future to expand and contract the layout as needed. I have two 100 lb amps on the top of one of mine with no problems. I would not recommend placing an amp in an enclosed rack as heat is electronics worst enemy. If you would like more details please PM me and I can give you more information.
Yamaha CX-A5000, ATI AT 2007 Amp (7X200W), ATI AT 2004 Amp (4X200W)Klipsch RF 63's - Main, RB 61's - Front heights, RC-62 - Center, RS-62's - Surround, RS-52's - Rear Surround, 2 Rythmik DS-1510 DIY Subwoofers (With PEQ600XLR3 Amp) each connected with Antimode 8033S-II, Oppo BDP-95, MMF-7.1, Project Phono Box RS, XBox 360, XBox One