Chad,
I would have to agree with the 1 gallon pots first, but I keep mine in 1 gallons for only a few months (about 3). As soon as the 1 gallon pots fill with roots, but before they become root bound, they are transferred to 5 gallon buckets. IMO, you will get much better and faster top growth in a short season if you follow that simple up potting procedure, because it increases the root mass (branching).
Check your local Plant Nursery, my local nursery usually has used 1 and 3 gallon nursery pots cheap, last year they were $0.20 each if I purchased 250. Good Luck.