The least expensive program I have found is with Assurant, though I don't right a lick of business with them (nothing wrong with them...I just don't do health). If you have an appointment with Assurant (as I do) you are then eligible for their sponsored E&O program, which you can pay monthly if you so choose. It’s $50ish a month.
Assurity, Mutual Trust, Ohio National, North American all (and I'm sure there are many others) offer a sponsored E&O, but you must have an appointment.