VEX has announced a new micro and accompanying electronics - which should hopefully mean that their current Cortex system will become cheaper secondhand. Lots of benefits to the new micro but for hobby use their Cortex is sufficient.

Also a lot of good programming options available with this system - the same ROBOTC for C-like programming/graphical as is used with LEGO Mindstorms, but also Python (https://www.robotmesh.com/studio-editions) and actual C (https://pros.cs.purdue.edu/)