It's not the most expensive ticket in the sport (and never will be as long as the Masters is around -- badge prices this year were insane) but the 2013 U.S. Open ticket is quickly becoming one of the most sought-after in recent memory.
The reason is actually just a simple refresher in economics.
Low supply + high demand = high price.
Here's the problem according to Philly.com:
"Due to the size of the course, the number of spectators allowed in each day has been limited to 25,000, not too many more than saw Bobby Jones win the 1930 U.S. Amateur, also held at Merion."
Compare that with, say, the Masters. Nobody knows exactly how many patrons are allowed in the gates at Augusta every year, but it's thought to be significantly more than 25,000. Heck, just three weeks ago I attended the Byron Nelson Championship, which saw 75,000 fans daily.
The point is, that 25,000 number is insanely low.
The price of tickets is reflecting it, too. Combine the low entrance numbers with a great season from Tiger Woods and this is what we get (all numbers are the best price you can get from StubHub):
Thursday ticket: $210
Friday ticket: $230
Saturday ticket: $260
Sunday ticket: $215
Full week: $975
Face value for these tickets is anywhere between $110 and $125. I expect them to go up between now and next week, too. As the Philly.com article pointed out, last year you could get tickets every day at Olympic Club for below face value.
And if Woods is even remotely in it on the weekend you can throw that $215 number out the window because people will be tossing around $500-plus without even thinking.