My sideline makes about $12k a year, costs around $200 to run, and has been running for 15 years. It's a room booking system for schools. I reckon I need to put

My sideline makes about $12k a year, costs around $200 to run, and has been running for 15 years. It's a room booking system for schools. I reckon I need to put in 2-3 weeks of work a year. I haven't figured out yet if I am a rubbish businessman or an excellent sideliner :-)