How much would you get for a model 29k53 singer sewing machine in good condition made in 1920?

The Singer Model 29 series came out in the 1920s and are still used by leather and shoe repair workers because of the long, narrow needle platform. They are incredibly strong and can actually sew through up to 1/2 inch of leather (or folded vinyl, canvass, etc.) and even 1/4 inch of wood. I've used mine for years making vinyl and leather upholstery in the process of restoring a number of cars. Depending upon condition, the value is somewhere between $300 and $800 these days, at least that's what you see on eBay and Craigslist.