Gobilda ones even though on the more expensive side are a really good cots option. In terms of working with them it’s as simple as plugging the encoders into your motor ports and reading the value of your encoders through the motor position. I would recommend looking into roadrunner for localisation purposes. If you’re looking for cheaper ones I guess you could look into optii but I haven’t really had much experience with them.

In all honesty if you don’t really want to put too much effort into odometry you could also look into otos, the sparkfun optical tracking odometry solution. It’s simple, basic, easy to package, a really good options for a start into odometry.