I wanted to bring this topic back up, after discussions in this thread I did some digging and am now using a 3rd party billing partner. I wont post it here, but if anyone is interested please PM me and ill give some info.
FYI They only do Fedex and only US but the rates are amazing.
I am curious if anyone else has used anyone, if so could you PM that to me too. My discounts are substantial but would like to see if I could even do better!