how much is...

well, it depends of the kind of computer and the configuration, a laptop computer is more expensive that a desktop computer, I think it would be between $200 dollar for a very old one and $2000 dollar for a computer with a big screen LCD and a very good graphics card and the last processor, a thing that can increase the cost in a computer is the software so a computer with Linux will be more cheap that a computer with windows, and if yourself build your own computer it would be more cheaper and you can put all the things that you want, it is good because not all the people have the same computer needed, I like build my own computers and I always put all the I want, I started with a very cheap one with a monitor CRT and now I have a better computer with a LCD screen. so it depends.

Here is USA a computer is about 300-600 for a good one.

when i buy my computer i buy the pieces and then mount the computer and i spend around 400€

here in Pakistan u can get one from 250-500 USD depending on how much loaded u wanna get

Here in the U.S., maybe $300-$600 for a PC and $1000-$3000 for an Apple.