Laptops maybe, but desktop systems are relatively easy to put together. The most difficult part (in my opinion) is deciding on what components to buy and making sure everything is compatible. Once you have everything it is just a matter of putting things together. For the most things will only be able to fit in one particular manner. You can't put RAM in a PCI slot, you can't hook up your motherboard power cable to a hard drive, etc. I would have to say the most difficult parts of assembly are applying thermal paste to a CPU (though most processors come with some pre-applied) and installing the CPU fan/heatsink (some just DO NOT want to go on).
mirdux, if you want to improve your tutorial I would suggest adding information about compatibility. For instance, your processor needs to match your motherboard (AM2, socket 754, etc.), your case needs to match your motherboard, you power supply needs to be adequate enough to power your system and have the appropriate cables/connectors. Also the motherboard usually comes with a list of 'approved' types/brands of memory. SATA hard drives require motherboards with SATA ports. The video card needs to match the slot on the motherboard (AGP or PCI-Express). I spend much more time researching products and compatibility issues than I do actually putting things together.
Great tutorial though, the pricing is relatively accurate (for now....most likely things will cost half as much in a year ). Nice overview of the components. Good work!