Cheaper?, well that depends on the price ;o) as for upgrading. Physically its not that difficult and in some notebooks its a doddle. Some have an access panel at the back for RAM and the hard drive is sat under the keyboard, the processor is also easy to get at.
I thought the answer to this was obvious, you can find parts for the pc everywhere, did you see laptop parts? also parts are not interchangable if you hav a compaq you have to get compaq parts, i had a floppy drive replaced on my laptop cost £125 including shipping and they wouldn't supply it had to return the machine, a floppy on the pc cost £8