JSCL is right - it varies dramatically.
In an airline operation, with the aircraft used 15 hours per day, figure on 10 cents per seat-km for the lowest cost carriers, and 14 cents per seat-km for the switched-on and lean/mean/trim larger carriers, and 20 cents per seat-km for the high cost legacy carriers. All in USD or AUD (they are about the same right now).
Boeing 737-800 @ 168 seats and an average block speed of 420 knots = 750 kph. 168 * 750 = 126,000 cents per hour = $12,600 per hour. A320 is approximately the same.
2 hour flight = $25,200. BUT you've gotta have that airline operation, a 30 minute turnaround at each end, and 15 hours flying per day.
A charter flight, where the plane flies out empty and back full, doubles the cost to $25,000 of course - provided the aircraft is busy with another 10 hours of flying that day. More than likely, the charter operation comes from a different airport altogether, the crew have to overnight somewhere, etc etc; and the cost can easily rise to $80,000 for the two hour flight. I saw exactly such a charter the other day - $120,000 for a 3.3 hours flight.