If you go through xpmedical, they offer free shipping on cases and a 5% discount for auto-shipment. So, I get Betterdrys from them at a cost of $94.99 for a case of 60. It equals $1.58/diaper. They are rated for 12 hour use, but let's say you use 3 per day. That is a cost of $4.75/day. This is based on size large and mediums are slightly cheaper. If you need protection you are paying at least something for the "cheap" brands. Looking on Amazon, Depend w/ tabs range between $0.90-$1.16/diaper (before shipping costs). So for roughly $0.50 more each, you can get a premium diaper. I know every penny counts, but spending less than $5/day for premium diapers isn't too bad in the scheme of things.
As for as the medical insurance including diapers...speak to someone overseas and they can tell you how much their government diapers suck.