I have several 500's, a 503, and some 401's. All are great machines and I think are some of the best machines Singer ever made.
My 500 is my main go to machine for everything. You don't need a cabinet or case for one. They were made to run on tabletop also. The 500 motor is actually very easy to service or overhaul. Even if they are frozen up you can fix them.
I always pick them up at thrift stores and garage sales because they sell well. They will last forever and are easy to get parts for.