Try Industrial Metal Supply they have cutoffs to 20 foot lenghts. Good source for clean new stuff. Also good source for 3003 H14 Aluminum, sheet metal for metalworking. I don't know if you've priced metal recently but bring a wheel barrow of money if you plan to buy a lot!
Yep, IMS in Kearny Mesa is where I get mine. Look in the cutoffs and scrap bins unless you need something longer or more specific in size.
this is exactly what i was looking for. i need to do a LOT of practice cuts/welds so this really helps. i am planning on sucking for quite a while and don't want it to cost me a fortune. gregg, what up!?