Add up all of the free items from one store vs. add on costs at another, ie. Most times you will find you pay less at a store that adds these costs on at the end. Remember there is no such thing as free anything. It was added into the cost of the mattress. That consists of putting a new cover over the old soiled one.
Nothing is done to rebuild it.
Once it is worn out it is garbage. Many times these have not even been sterilized and can be contaminated with urine, bugs, mold and meldew. Gosh knows what else. They can be the cause of many unknown health problems. One stands head and shoulders over the rest and it is not the largest company.