Servos (hobbyist level) are a dead end in this application, but even marginal quality BLDCs are quite a bit more expensive. These servos can be swapped out for

Servos (hobbyist level) are a dead end in this application, but even marginal quality BLDCs are quite a bit more expensive. These servos can be swapped out for BLDCs in a retrofit, so I think this is a good starting point that can be expanded on.