If you don't have time to sell it, consider donating to Goodwill or another charity. Folks go through there lots of times looking for stuff just like what you have.
Additionally, it would give you a tax write-off for donating to a charity.
If you can, however, hang onto the machine. It has kept it's value over the years. You know it works. If you ever need to hem some pants, or fix a seam that splits, it is easier to pull out the machine and do it yourself rather than take it to a seamstress and pay to have it done.
Hey, check out your local drycleaner - they may have a seamstress who would love to take the machine for $100 or so. Or, ask someone at your church or local fabric store or someplace advertising veteran's organizations - since they do Quilts of Valor. How about your local shelter. There is probably someone at those locations. Post a note where you work - someone there might be interested.
Good luck!