Interesting build, very time intense to make, but the author got a roughly 100 watt unit running. The cheapest I have seen that is similar to this is Harbor Freights Solar kit which on sale goes for $120 for 45 watts (currently at $200). But you don’t have to make your own panel from scratch.
Me, I might wait for the HF sale again.
http://www.harborfreight.com/solar-panel-kit-45-watt-68751.html#.UyHaZ3VDtu4
http://www.instructables.com/id/Solar-Panel-Setup-around-100/