Not too bad
I agree. $200 to self publish on a platform that displays the book and collects the money is not bad at all. Paper self publishing is far more expensive. Also, the cost of providing your own book, with licensed DRM on your own web site, which you have to pay someone to design should be quite a bit more.
Nevertheless, I agree that if you can convert to BBEB yourself then they should accept the work withour requiring the outside service.