I'm a physician, and every insurance company to which I submit claims already has a web service in place to check eligibility...at no charge. Already.
There aren't many interface differences between insurance companies: you typically enter two identifiers, usually either an id number or last name, and birth date. You get full eligibility info immediately.
There's nothing difficult about it. We almost never call insurance companies to get eligibility info - web querying is already in place, and has been for a while.
What problem, at 5 cents for each API CALL (c'mon, really?) is this solving? Why would I want to pay to pass my patient's protected health information through yet another layer (and store? see my comment below about this company's offer of a data "sample") of potential privacy loss?