IIRC, I paid around $700 for a new 1972 CB350. The same year I bought a new Fiat 128 two door for $1,800.
Not sure about BMW getting into the 500cc market. There is a whole lot of competition from the far East in the lower displacement market. And like Hyundai they are improving the offerings and quality every year. Even though BMW would likely build these bikes in other countries, could they still price the products competitively.
EDIT:
The BMW scooters are Kymco......but still sticker at $11,000 on the showroom floor.
Not much price advantage there. For that kind of money, get a motorcycle.