I can't read what it says on the top tube, but that is the model name of the bike. It might be a Nomade, or a Mirage.
Here's the catalogs. Maybe you can find it in there.
https://bulgier.net/pics/bike/Catalogs/Motobecane/
If the bike is 1020 or 2040 steel, then it is probably going to weigh around 29 lbs. or so. Depending on what you want the bike for that might be heavy, but if you are going to run errands on it, not so much. If it has steel rims, and it might, then stopping is not the greatest especially in wet weather. If you do buy it, change the wheels for alloy if you can and if not, invest in some better brake pads. There are a variety available now that will improve braking for you.
I wouldn't pay $300.00 for it, not even half that. But I think $75.00 might be too low in many markets. Bikes have increased in cost and even the bottom dwellers have increased.