a few years ago it used to be the opposite way, you could build a pc for much less than any retail outlet, today its the other way, BUT
what are you actually getting? you may see a system thats listed as:
blah blah512 ram, 200 gb hard disk, 3000 mhz cpu
ok, you can get 512 meg of ram retail for under £30, you can also get 512 ram for just under £100 retail. The difference being mainly the speed, people dont realise this, they just assume because they dont know. Almost likewise with the hard disk.
Users dont know or care what a motherboard is, but in fact it makes a LARGE difference to the overall stability and performance of your computer, prices vary from £30 to over £100 - and like a lot of things in life, you get what you pay for (generally)
I do custom builds, but not often because of the above reasons, people say "I can get a Dell for much less", I tell them to go ahead, if a customer requires a high performance machine, I'll tell them to buy a £399 dell then bring it in and compare it to my "ancient" 2600 machine that would still cost about twice that of a off the shelf pc from Dell or anyone elsef.
So as far as making money from hardware, unless you are either selling performance machines, cheapo machines, or components then I'd say no.
Sorry my reply is somewhat rushed but I just realised the time and I'm up early!
Refreshit, I'll pm you tomorrow