The decals are in great condition. Usually, it is merely a matter of gently cleaning and greatly oiling anywhere metal meets metal in the mechanism. If it is a back clamp, accessory feet can be found, but are pricey.
Often sewing machine cabinets get used for (overwatered) plant stands, and the top of the cabinet ends up with watermarks, cracked, and lifting veneer.
If the top is in good condition, and the back of the head looks good, go for it. $80 is not out of line. A leather belt can be had for under $10, and their are many suitable alternatives, even cotton clothesline, or window screen spline.