Freight is a important factor in the price of grain. When the brew store is also connected with a brewery the quantity bought makes the freight less per bag. My guess is that they are also getting a significant price break also.
Rahr 2-row is $36 and Breiss is $37 in Plover WI. There is another 15% discount on the next purchase after you spend $200 on their rewards program. I stock up big when I use that.
I am looking at doing the same except using this switch: http://www.homedepot.com/p/t/100356941?langId=-1&storeId=10051&catalogId=10053&N=5yc1vZbojhZwcZ1z10sca&R=100356941#.UWYMki0o6P8