I'd agree that 2 row is the way to go for a bulk purchase. The only problem is the shipping cost.
Some places give you a discount for the sack, but charge exorbitant amounts for shipping. Other places charge more for the sack, but give you flat rate shipping.
The closer you are to the distributor, the less the shipping costs should be.
You may also be able to buy from a local brew pub or your LHBS. I bought 2 sacks of Maris Otter last month from my LHBS. It cost me $106.00. It would cost me $177.53 from Brewmasters Warehouse.
I'd definitely check out
The Country Malt Group where you may get some good shipping rates.
-a.