Most knifemaker suppliers will carry some knife steel. Your best bet is probably going to be to order a stalk from one of them then cut to length yourself. If you have the means of cutting out your own pattern, you have the means of cutting to length. A cheap angle grinder with a cutoff wheel will do the job.
I would put my vote in for either 5160 or 1084 for your starting steels. You'll get the best performance out of the simplest heat treatment out of them should you decide you want to learn to do your own heat treatment, and they make excellent knives regardless. I talked about my heat treatment methods for these alloys on my blog recently under the post "Why I make what I make the way I make it".
As for suppliers, you won't be able to walk into a steel supplier and expect to find anything that isn't mild steel. Order from a knifemaker supply, such as Jantz, Texas Knifemakers Supply, Sheffield, Admiral, or Aldo Bruno (whose name is a byword in the knifemaking world).
Find a heat treater and make sure what alloys they work with. I was talking with a guy recently who was wanting heat treatment info, and I suggested one I had heard of. His response was that he'd already talked with them and they didn't do 5160, which seems odd to me because it's a boneheadedly simple heat treatment.
How are you planning to shape the knives?