I’ve been buying from Horsetech for years now, and they’ve consistently provided the best product and astounding customer service. My orders always arrive amazingly fast too.
http://www.horsetech.com/
I get my flaxseed from them, a custom Nutraflax-based mix that is formulated specifically to my specs. Those specs are based upon my yearly hay analyses.
I also buy their dry vegetable oil; it’s way better than messy “wet” oils.
The “icing on the cake” for those who have US Rider memberships (US Rider being the roadside assistance organization… www.usrider.org ), you can get 10% off every purchase from HorseTech.
Oh yeah, that little bag of Famous Amos cookies they put in every order is a sweet touch as well.