Freddy,
Surprised you find slippery elm expensive.
I find it cheap as all... I get mine as organic slippery elm powder - costs about $20. per pound - I get mine from mountainroseherbs.com.
At 3 teaspoons per day, that would last you about 56 days -to me that's pretty cheap.
I used to get mine in 2 pounds shipment (to save on shipping fees) and it would last 3 months. Now since being in remission, I only use it once a day, my 2 pounds last a good 9-11 months.
Ideal dosage is about 1 heaping teaspoon, taken in a little water, with the probiotics in it, after each meal. Take your meds 3-4 hours apart from that. That's how I take it, and it's been very effective.