Scaling up NTC measurement through Multi-Channel Ohm meter
At the quantities you desire, it would most likely be best to design a custom PCB with a micro with CAN bus, and ADC and an OPamp could be had for the 50$-70$ range depending on your requirements. (0.1C 0.5C or 1C accuracy?)

The circuit looks like this (doesn't matter if it's a PTC or NTC): 

Source: Here

An add on board with analog for an RPI would probably be in the same  price range. If you did multiple channels on the same board the cost would go down even more. Depending on the accuracy and temperature resolution, maybe less. There would be an additional cost of time and software writing for the custom solution.

Another option that might work is the LTC2986 which has a demo board with an 'arudino' (actually linear's own flavor), if I remember right they have at least 4 channels (or 8) with 0.1C accuracy.


Source: Digikey.com

With a one of these solutions the NTC's may also reqire calibration (depending on your accuracy and resolution requirements) with a bath or some other method which might be more complexity