It's worth distinguishing between two completely different types of "servos": RC hobby servos, and industrial-type servos which are robustly built like steppers but significantly more fast, accurate, efficient, and powerful. They are hard to find in Nema 14/17 sizes but not impossible.
RC servos typically have an analog or PWM signal interface. That would usually not be accurate enough for an industrial servo in positioning mode. Industrial servos, like steppers, have a digital interface which might be a serial format or STEP/DIR pulse train. Some drives will accept a -10V to +10V analog signal for velocity or torque control mode.
Anyway, here are some Nema 14/17-sized industrial servos with online pricing, which might be what you're looking for?
Thanks, lots of helpful links there. Much appreciated.
Although quickly checking, I suspect they could be over an order of magnitude more expensive than the hobbiest equivalents.
Somewhere between 1 and 2 orders of magnitude more expensive though not without a reason- increased demands for design, manufacturing, testing, reliability and having to support the product for several decades costs money.
The cheapest of RC servos have a lifetime of a couple hundred hours max, even at less than half of their max torque (if their manufacturers would even specify what is the rated torque). I have one fail after two days of operation with a full rotation every 15 seconds with very light load. There are of course properly built RC servos- with serial communication for feedback, metal gearbox, brushless motor- but those start at ~50EUR-100EUR.
IMO the best bet for hobbyist is NEMA17/14 motor with a driver that has rotary magnetic encoder on them- there are cheap and open source options for that.
Next best thing would probably be a BLDC motor (optionally- geared) with SimpleFOC.
RC servos typically have an analog or PWM signal interface. That would usually not be accurate enough for an industrial servo in positioning mode. Industrial servos, like steppers, have a digital interface which might be a serial format or STEP/DIR pulse train. Some drives will accept a -10V to +10V analog signal for velocity or torque control mode.
Anyway, here are some Nema 14/17-sized industrial servos with online pricing, which might be what you're looking for?
https://en.nanotec.com/products/2262-smart-servos-motors-wit...
https://catalog.orientalmotor.com/viewitems/l-categories-ser...
Or many companies offer stepper motors with built-in encoders and controllers to prevent missed steps:
https://catalog.orientalmotor.com/viewitems/az-series-absolu...
https://www.zaber.com/products/stepper-motors/X-NMS-E