Bright eyes - you might try checking with your local feed mill / store about whole flax seed. I get 50 lb bags of whole flax seed for $35. You don't have to feed much of it, so it lasts a long time, and I think it ends up being less expensive than cool calories. Some people grind their flax in a coffee grinder - if so, you have to do it right before feeding, as it isn't stable once ground and loses nutrients rapidly and can go rancid quickly too. I just feed it whole, there have been studies showing that the horse breaks down the shell adequately and extracts the nutrients just fine.
I used to feed my horses soybean oil for fat, and saw a huge improvement when I switched to flax seed. We're learning more and more about how important that Omega 3 : 6 ratio really is.