Hard question!
They didn't give a name brand?
Without a better picture, it's hard to tell what it is...and it looks like an early Wheeler & Wilson did....
That being said, for something that looks that good, and if I had the money, I'd probably go as high as $300-$400 for it...depending on what it is and whether or not it is actually a French machine.
Needles will be difficult, at best, to find...attachments nearly impossible. Sure would look good in a sewing room tho!
Be careful of the "only 1500 made" claims.... folks say that about the Singers all the time, because they will see the serial number listings and for example, it will show a 15-91, made on a certain date in 1946, and the allotment number of 5000, and they'll assume that there were only 5000 of the model made, when in fact there were millions of the 15-91s, just that they only made 5000 in that run of them.