Can a motion sensor switch be installed as part of a pair of switches?
Your switches and lights are wired in a "three way" configuration, so you need a three way motion sensor switch.

For example: the Eaton OS306U, although there are a variety on the market and they do start around $22.

Important things to note:


You probably need a model rated for "No Neutral Required", depending on the wiring to that box by the garage.
If you use Florescent or LED lighting make sure that the switch is rated for it (most newer ones are).
Make sure that the switch is rated for the lighting load you have.  Most such switches are rated for 5 amps / 600 watts.  If you have more light than that, you need a pricier switch.
It sounds like the current switch might be miswired.  Consult an electrician if you are not 100% sure.
Good photos of the switch and wiring, posted in your question, help us give more specific and tailored answers.