It's very slim pickings. There are a very few metro ethernet providers here. If you don't have fiber to your building, you are probably relegated to bonded T1's. Once you get over 8 T1's, you are probably looking at a T3 (DS3), or a fractional T3 if available.
Either way, you are talking about some serious jack.
You may want to post here for a quote: »ISP b2b etc
Charter has 50/5 service, but ... it's Charter. You might consider 2 x 50/5 connections. You'd probably have to load balance on you own, and bonding would not be an option. That won't work for many situations.--
I just might be the most "licensed" S.O.B. you know.