When I buy "new" metal stock, I get it from Online Metals, since they are only one state away from me, in the western USA. In the east, you might want to try Metal Express. Finding a supplier near you helps, since you're ordering heavy stuff, and freight adds up.
Most of the round and hex stock I use comes from a screw machine shop about 50 miles away from me. If you can find one in your area, it could supply most of what you need at scrap prices. Screw machines can't chuck up the last six inches or so of stock, so it ends up in the recycle bin. The place I visit usually has tons of it in barrels.
There are some sellers on ebay, too, who sell cut offs, and will ship in Post Office flat rate boxes, so from some of them you can get 20-50 pounds of scrap and the shipping will only be $10-12.
Dean