I picked up a pair of Optimus STS 50 AV bookshelf speakers for $15.00 and they sound nice but are looking dated. The vinyl coated cabinets had a few nicks so I scuffed the cabinets with 220 sandpaper and applied two coats of flat black enamel as a base. They were finished with two coats of Krylon "Make It Stone" textured spray paint in black. I used half a can of Krylon on the two cabinets. Total investment was around twenty bucks. The Krylon textured paint is available in different colors and a base coat close to the color of the finish coat is recommended. Link to before and after images...
http://neuro.smugmug.com/Other/Optimus-Speakers/27837639_FZkFPd#!i=2348021406&k=nwzZXGn
http://neuro.smugmug.com/Other/Optimus-Speakers/27837639_FZkFPd#!i=2348021406&k=nwzZXGn