A wonderful restaurant in the 6th is La Bastide Odeon, that we originally found in Patricia Wells's book, and enjoy on every Paris visit.
The food is superb and the waitstaff excellent.
It is smallish, as stated above for Paris restaurants, but last month we were 7 people with no problem. Perhaps they could seat 2 such tables adjoining? There is also an upstairs area that may be larger.
The price range is about what you stated.
www.bastide-odeon.com