Walmart carries black and charcoal carpet. It's not top of the line, but it'll get the job done. If you don't have an air compressor & spray gun, you can get by with 3M Super 77 spray adhesive.
The process is nowhere near as difficult as many people think. Just watch one of the many online tutorials and you should have a pretty good idea how to do the job.
Elemental Designs has a tutorial video online. You should be able to find it on youtube...
//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gifwho said wally world carpet? Fleace man.