The bikes that the average truck-loader comes in contact with cost $120.
Edit: Sorry, I should have made that clearer in my previous comment.
Don't forget that "good bikes" are actually very rare, especially if counted in volume (not price).
You can buy an adult mountain bike for £80 including 20% VAT in the UK. That's $100.
I've used one like this, it lasted less than 6 months of daily use before the sprockets, wheels, bearings and brakes were ruined.
http://www.tesco.com/direct/north-gear-rxt-mens-adults-mount...