Well, I pick up brass for a couple ranges (as you may have seen mentioned elsewhere...) and I do fairly well for hobby money.
I probably take in anywhere between half a ton and two tons a month! Figure that at about $.30 per pound, and about $.20 per pound for Aluminum. Steel ain't worth the gas to haul it in in any amount less than a long ton...
I also go thru all the brass I get and remove live rounds (it's the arrangement I have with my scrap buyer) and demil the live duds seperately. Warlord is correct in saying that many buyers won't take brass - citing "liability" issues. Considering that brass MUST be crushed in a press before melting it (at least, thin sections like cartridges) a live round won't pose that great a problem in the foundry - sweating into the melting pot is actually more dangerous than a couple live rounds would be!
If you can, wait until you get a 5 gallon bucket full - that will be about $15. A full 5 gallon bucket usually tips in at about 50 pounds for brass, and 20 or so for Aluminum...
FFZ