Tony, I use Beet pulp a lot. At home in the winter when the weather is really cold, I will soak it and feed it along with hay to add extra water to the horses diet during cold weather.
At trail rides, I offer the horses a drink. When they are done drinking, I then give them soaked beet pulp as a way to cram a little extra water into them.
My horses eat beet pulp with gusto. So I can easily add just about anything I want to slip into the beet pulp and get the horses to eat it. Electrolytes being a prime example.
Around here, I can buy beet pulp pellets for about $10-$12 a 50lb bag. So they are priced similar to other feed products. They broaden the mineral and vitamins that my horses would normally get just from hay.
There are some good articles on animal nutrition that discuss what beet pulp offers in the horse diet. Especially in the distance horse.