A lot of bikes tend to gravitate to around $300 or so. I'm not surprised to see a mixed groupset with Campy shifters/derailleurs, ??? crankset, and ??? brakes.
Hmmm... The specs suggest Universal brakes, but I think those may well be the Weinmann in the photos.
It looks like the 1973 catalog lists Weinmann center pulls.
Motobecane catalog (1973)
Dates that sellers put on ads are often off just a little bit. And, catalogs may also be off some, especially if Motobecane made one catalog for multiple years.
Not much wear on that seat, but the paint has seen better days, and likely will get worse over time. I have a Mirage that the paint looks just about like that. Yet, Mom's Grand Jubilee looks almost immaculate. But, I wonder if Motobecane has had issues with the paint, especially if the bike has seen some sun and weather.
I'd rather see the bike for a little less. $250??? But, truthfully, at $350, you're not too far off on the price.