It costs them money everytime someone calls an 800 number.
Lets get busy.
Not much. 3uTelecom charges their 800 customers 4.8 cents a minute for incoming calls. If you really want to do it right, you go to a pay phone and call their 800 number. Then they get assesed 65 cents per call to reimburse the owner of the pay phone.
Still, I wouldn't bother. Assuming these are facts, these people will have moved on very quickly when the flack starts hitting.