In the most recent CMASS Zoom club meeting, there was discussion of the Estes C11 Motors. Hobbylinc has a special this week on bulk packs of C11-3 motors:
Check out AC Supply. Best prices on rocket engines and other rocket related items. They only carry Estes. www.acsupplyco.com/estes/engines.htm $28.78 for a 12 pack of C11-3's.
Hobbylinc used to have the best prices for Aerotech single use composite motors.