Christy,
I have two Singer 9W-7s which is the later version made after Singer bought out Wheeler & Wilson. They are fine machines. Very smooth, very reliable, very simple machines.
There are only two things that 'might' cause trouble. Needles, and bobbins. They use the obsolete 127x1 needle and the curved sided bobbins often referred to as doughnut bobbins. The needles are very scarce although they do appear on eBay occasionally. The bobbins are, I have read, even harder to come by.
There is a substitute needle for the machines, but the biggest they can be had in is Size 14. I don't find this works well for me.
If you can get past this, go for it.
Joe