The first thing you see when you arrive in a foreign country is usually a taxi. Whether exiting an airport or crossing a border, it's the taxi drivers that first make contact. The question here, is how much should you be paying? Pay too much, and they'll get used to ripping off uninformed visitors, pay to little and maybe you'll end up in an alley.
I forget where I first learned this trick, it may have been from some stranger while riding a chairlift, it may have been from a fellow traveler. The best thing you can do is to ask a local "How much will a local beer cost me?"
To give an example of why this works think of your local restaurant. To get a taxi ride to the restaurant it's about $10, or two beers. To eat, if it's a cheap place $10-$15 will get you an entrée. That's two or three beers.
Now let's think of it in terms of travel. In Mongolia a beer is $1500 Touareg. A taxi in Ulaanbaatar will run you $3000 - $3500 Touareg. So expect to pay about the same for a meal.
Get the drift? Try it out and let me know how it works for you!