Hi Paula
You asked: Fuel quotes actually doubled the tour price. Is this reasonable?
Yes it is reasonable. The distances are enormous.
Here are all the figures you need to calculate the cost.
The distance from Ulaanbaatar to Dalanzadgad in the Gobi is 600km
From Dalanzadgad to the popular spots in the Gobi add another 400km
So a round trip would be around 2000km
A Russian jeep will consume every 5km - 1 litre of gasoline.
1 litre of gasoline costs about 1300 Togrog
Now the calculation
2000km / 5kmPerLitre = 400Litre of gasoline for the trip
400Litre X 1300TogrogPerLitre = 520,000 Togrog for gasoline for a Gobi trip
520,000 Togrog / 1400TogrogPerDollar = $371
A cheap jeep might cost $40 per day
$40 X 8days = $320
As you can see the jeep cost and the gasoline cost are about the same.
Add guide cost, food and lodging to figure out the total cost.
To reduce the price people find trip partners to share the cost.
See the ToMongolia Tour Operator page for more calculations.
The figure you have of 300km will get you only half way to the popular spots in the Gobi
I made a map for you showing the distance between Ulaanbaatar and Dalanzadgad
Dan