Eggcrate Acoustic Foam
For a more economical solution to soundproofing, eggcrate foam performs well at a lower price than wedge foam tiles. The style of eggcrate foam keeps the price down, yet it still performs well for someone needing soundproofing on a budget. It is especially practical for people planning to cover their deadening foam with acoustical cloth.
More information: http://www.thefoamfactory.com/acousticfoam/eggcratefoam.html