Wow, a company that would pay for all my ebay fees? Come on, think about it. How could a company stay in business by paying all your ebay fees for a fix rate? The purppose of a company is to make money. Pure and simple. The use of money cost money.
To pay your listing fees means that company has to not only recover those fees somewhere but also make a profit on them to contribute to the bottomline. They charge $50 a month for unlimited listings? There is no way that would cover the ebay listing fees. If it smells then it probably is "it"!