Looks like Hobbylinc has some Quest A6-4 / B6-4 bulk packs and three packs of C6-3 / C6-5 in stock.
Quest/AT must be clearing out the old BP stock to make room for the new composite motors.
https://www.hobbylinc.com/quest-model-rocket-engines-educator-packs
https://www.hobbylinc.com/c-model-rocket-engines
Quest/AT must be clearing out the old BP stock to make room for the new composite motors.
https://www.hobbylinc.com/quest-model-rocket-engines-educator-packs
https://www.hobbylinc.com/c-model-rocket-engines