To me, it really looks like an old Singer. It's better than any of the ones I've picked up in carry cases, as I see it has decorative stitches. The ones I find are usually basic machines, but this one looks more top-of-the-line for its day.
Cleaned up, in working condition and in its carrying case, a machine like this would sell for about $30 in thrift stores in my area. It would be considered a vintage machine, although not necessarily collectible. If I didn't have other machines, I would use it as a backup for my Bernina. But, as I said, this is the type of machine I look for in the $5 to $30 range to fix up for donation to the non-profit.
Does it take cams? Or can you do the decorative stitches without cams? Without cams would make it a newer machine (than one that needs cams), I'm pretty sure.