The self tapping screws worked great - i definately suggest going that route.
I built a 10 rack and a 7 rack with the stuff below but here are the costs as best i can split out for that unit. I had extra left from what is listed below for a 2nd rack...

Total costs:
2 5'x8' boards, cut $190
16"x10' boards $60
Screws $2
8-15 qt/6-31qt $94
Flexwatt 23ft $54
Total $400