Price Analysis of Continental Flight From RI to OH

I recently flew on an Embraer RJ145 from Providence to Cleveland and in an attempt to learn something was wondering how much it must have cost the airline to fly there. I came up with some really shaky estimates that I would like to share. Please take a look at the following additional information which will help us do the calculations at the end.

Talking with people on the flight it seemed that a two way ticket averaged around 200. So one way is really roughly 100 not including taxes.

The embraer can hold 50 people and had about five seats empty, so ticket sales accounted for roughly 4500.

The embraer has a fuel capacity of 4173kg and range of 3704km

The straight shot distance from Providence to Cleveland is roughly 900 km so if the full range is 3704km that means we flew at around 24percent of the range, using 24 percent of the max fuel capacity ignoring wind and other factors.

According to some shaky air fuel websites I found GradeA Jet Fuel is around 6.10 a gallon right now. Assuming jet fuel weights about the same as water (which it probably doesnt), 1gal of water weighs 3.79kg so follow along now:
We used 24percent of 4173kg of fuel so 4173 (times) .24 equals 1001.52kg

Now convert kg to gallons (which is impossible I know, but lets assume its density is similar to water)
1001.52 divided by 3.79 equals 264.25 gal of jet fuel
Jet fuel is 6.10 a gallon 6.10(times) 264.25 equals 1611.93

Lets also assume the pilot gets paid 50 an hour (pilots can only fly 20 hours a week) the flight took 1.5 hours. Co-pilot 30 an hour Flight attendant 20 an hour
50(times)1.5 + 30(times)1.5 + 20(times)1.5 equals 150

Ignoring all other costs (initial cost of the plane and maintenance, ground crew, air traffic control, bagage handling, taxes...etc) in a mega rough estimate it looks like it costs 1761.86 for continental to fly from Rhode Island to Cleveland. Take ticket sales and subtract that and your left with 2749, but I imagine the costs not calculated suck out a lot of that. Something ingenious that Continental does is to have their own print magazine for each passenger on the plane. I found this to be pretty clever as a subtle way of getting at a captive audience.