negotiating a flat rate with a hospital due to private insurance not covering maternity

I live in the Washington, DC area and I'm hoping I can get some specific advice from moms or moms-to-be who have had to make the same decisions I'm facing...

I recently left my job (and therefore my wrap-around group insurance) to start my own business and I'm looking at my private health insurance options.  I'm not pregnant yet but I plan on starting to try in the next few months.  While I have found one plan through BCBS that I can add on maternity coverage (pre/post natal care and hospitalization) for an additional $126 a month, I've also been told that it might be more affordable to negotiate flat rates with my OB-GYN and hospital. And let's be honest, I'm probably going to get denied for the plan that I am looking at!  

I already spoke to my OB-GYN and they said they have a flat $3500 rate for pre/postnatal care, vaginal birth etc.  I have to negotiate with the hospital separately.  While I'm looking for specific recommendations, I'm also looking for ballpark figures to help me weigh the decision of adding on maternity coverage to the health insurance plan I end up with.  Even if the plan I go with doesn't have maternity covered, I am going to make sure it covers it if there are complications.  The thing is, since I can't predict the future, I have no idea what questions to ask or what loopholes my insurance, doctor or hospital might find where I end up footing a big bill.  

I've been told about Aflac's supplemental maternity insurance but when I called them, they explained that they no longer offer it!   

Thanks in advance for your help!

 Leslie