I have had 6 or 8 of them run through my hands and I really like them, but they are a heavy machine! I like them because they are easy to use, parts are readily available and they are a really good looking machine. I have converted one of mine to a Handcrank and I have one I will use in a treadle. It is a 3/4 machine so if you do put it in a treadle or cabinet find a 3/4 treadle or a 99 cabinet (super rare) or make and adapter plate for the existing cabinet.
For one that needs servicing I would not pay more than $30 but it should all be there. Be careful of the original green case, they will rot through the years and if you pick it up by the handle the machine might fall out of the bottom. A good case is really getting harder to find with these machines, and sometime the case is worth more than the machine.
Here is a repaint I did for a little girl last year for Christmas....
Billy