You cannot throw a number of zeros on a domain name cost simply because of the extension without factoring anything else in, it does not work like that; though you can have a good guess at the likely outcome due to millions having been sold now giving us statistics.
On average .net sells for 10% of the cost of a .com and .org sells for 30% of .net but your reasoning is flawed, it assumes that every domain is equal when they are not.
Cyb.org for example is worth many times more than almost everything else in that extension and even in .net and .com even because it is the only domain hack possible and is perfect (to me at least) even though the constituent letters mean nothing to no one.
Similarly something like creditcards.ch would be next to useless in somewhere like communist China right now since without even having to factor in that no one would be looking for it or the obvious political reasons, they use a different letter set altogether so you would only find curious travelers looking and not many of them.
However Rice.ch I would guess would have a price going through the roof.
3 letter domains are the same, those that have meaning and can spell something out will be generally worth a lot more than those with random letters but it is not always the case because lets face it, zzz doesn't spell anything out but it would be perfectly brandable for a company making a sleep drug like Nytol.
Similarly cars.tv is next to useless in Tuvalu because they don't buy many (though they have a high number of cars relative to the amount of roads though mostly government issue) yet it would work perfectly in the Western world to make a satellite channel and bring in huge prices. Think of Top Gear in England.
All pricings are subjective, but you can look at the population of the country you are basing it in and guesstimating what they would be most likely to search for and thats the issue we face all the time, Americans or English are not going to search for loans or credit cards in Albania are we?
Generally speaking for you though .com is worth the most followed by the most powerful of country codes such as .de or co.uk with .net and maybe .in jockeying for position with them and .org bringing up the rear. The rest of the other extensions around the world are simply duking it out to survive in a lonely world and that is where your keywords and research come in.
With the exception of elite keywords in general that keep going up for now every other domain is in a constant state of flux and that is what is fun about it, I personally would hate for some corporation to come along and think it has the right to stamp a price like all we are doing is playing with tins of beans. This is the last bastion of real free barter and trade in the world and I would give it up for nothing.
Any one of us can become a millionaire overnight if we recognise something others do not or stumble on a rising technology that goes global and happen to have the domain name. I am betting the guy who bought 3d.tv all those years ago didn't have a clue that everyone would be fighting for his domain :p
