Remember, those big basement finishing system companies make lots of money (your money) by selling the complete package--materials and labor. In fact, you cannot separate the materials from the labor.
But what it you could get the materials alone and do it yourself? One company that I know of, Wahoo Walls, does this.
Wahoo Walls' pricing is transparent ($199 for a 4x8 panel, with a sample 1000 sq. ft. basement coming in at about $6,600 - as of November 2012) and they give you lots of DIY design suggestions.
Downside with any big remodeling materials ordered online: freight costs. Unfortunately, online estimation of freight costs isn't yet available at Wahoo Walls, but they say it is coming soon.