I thought I'd add my experience with Encore metals. I got two sticks of 4140 (SPS) steel from Encore Metals on Friday. Price was okay: $105 for 24ft of 1/2" dia heat treated/ground stock, and $120 for 20 feet of 1" annealed stock (which will need heat treating).
they gave good service, only sell in full lengths, price was as expected. They were happy to cut them to a specific length (+/- 1/4") for transport.
One wierdness: for cash sales (via credit card) the don't give you a receipt or invoice. You have to specifically ask for it.
Oh yeah: $200 minimum (but for full lengths, it is easy to go over that)