IP is what I tried before surgery and now I know I don't need surgery! (well, maybe a panniculectomy at some point but not WL surgery!)
Besides, you're right, you'd be doing this after surgery anyway!
DH and I decided that yes, IP is expensive but so is bad health so we chose to give up other things and spend the money on my health before it deteriorated further.
Once I got a FIRM hold on the plan, I ventured into alternative products. I went competely alternative product in August, mostly due to how disgusted I was with my clinic at that point.
One of the things that really pushed me that direction was going soy/gluten-free last January after I started having thyroid problems. My coach didn't like that I was using alternative products but IP just wasn't offering the variety of products for me that were soy/gluten-free.
My recent post here will give you some ideas for soy/gluten-free alternatives
Of course you don't care about the soy protein but it'l at least be a start for you.
I'm here to say: If I can do this, ANYONE can!