Our group was a bit bigger, but we took 122 high school students and 18 chaperones from PVD to MCO. We were split into two planes due to the group size, you shouldn't have that problem. The fares were about $80 roundtrip after discounts, but we purchased very far in advance. Since we were going for Magic Music Days, Disney handled the reservations for us as part of the package.
One bad thing about being a larger group - SWA made us board after the the non-group people (i.e we all got "C" passes). As bad as that sounds, most people chose not to sit apart as they didn't want high schooler's talking around them the whole flight.