The Motorola Radius SM-series radios are discontinued land-mobile radios (FCC Part 90) that are available used for under $50. The VHF models can be converted to work on the 2m band, making them an inexpensive option for a dedicated APRS radio.
This article goes over the features of the radio, what you will need to set it up as a dedicated APRS/packet radio, how to program it for the 2m ham band, and my failed attempt to make it work for 9600 baud.
Making these work isn’t for everyone. You have to be a little technically adventurous. But if you want a mobile packet radio for very little money, this could be for you.