I get my sheet aluminum from Speedy Metals on Ebay. It costs ~$21 with shipping for me to get a 1/8" thick x 6" wide x 48" long sheet of 6061-T6 aluminum. This is what I used to cut my buggy's chassis. They also sell other aluminum, like a 1/4" thick x 2" wide x 48" long sheet of aluminum, which is what I used to make the motor mount on my buggy.
http://stores.ebay.com/SPEEDY-METALS...toreviewQQtZkm
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz