I did some research on the topic, and, it's probably location.
LocalBitcoins is NOT an online exchange necessarily, it's a road map that leads to bitcoin-to-cash brokers.
In Chicago, you can get away with $100 a coin, but some of these places more dislocated (and american) would make perfectly reasonable places if you're a doctor who defaulted your college loan or something and won't be using an exchange any time soon.
At that you're seeing the sales of all the cash exchanges. In april a few coins went for $400.
Hey, I sell bitcoins for 500$! Wanna buy some?
That doesn't mean people will actually buy it.
The chart lists past sales, not past offers.
On localbitcoins when buying with cash:
1) You pay premium to meet up in person.
2) Some people are a newcomers wanting to buy their "first" bitcoins.
That makes it an ideal place for an occasional ridiculously high offers.
Absolutely.
