Both "cheap" and "useful" for running Tor nodes at home won't be found in big box retail ever, so I would take a look at the Mikrotik RB750Gr3 - it will do exactly what you want after it's configured properly. I used to have an
RB1200 and recently upgraded to a CCR1009, both from Mikrotik, and have found them to be quite capable under heavy load.
Make your day great,
Isaac Grover, Senior I.T. Consultant
Aileron I.T. - "Practical & Proactive I.T. Solutions"