Try spice racks on Amazon. They look like little steps, and can hold 2 rows of Citadal/P3, or 3-4 rows of Vallejo/Reaper/
AP.
Ones that are made for paints are stupendously expensive.
I have several of these:
http://www.amazon.com/InterDesign-Twillo-Stadium-Spice-Metallico/dp/B0052WG1G8/ref=sr_1_1?ie=UTF8&qid=1415039383&sr=8-1&keywords=interdesign+spice+rack
They hold 45 Citadel paints -- 15 per row (7x2, plus a gap to fit in one more), and obviously more of every other brand.
There is a narrower version that has deeper shelves that I use for Vallejo, because it fits 4 per row.