What is the value of singer sewing machine no 99-13?

I've bought a lot of the 99-13 models. I love to fix them, and resell them because there isn't a better machine for sewing heavy fabrics or just about anything, for the money today. If you are lucky enough to find them for 40 or 50 dollars, then you might spend the same in getting it overhauled and the engine greased....you just have to be careful it's a project you want to take on. Once restored to working order, I think the value ranges between $160. and $275. depending on the condition of the machine.