Best way I can explain it is this...RGIII was the #2 pick...not the 4 spots they moved up. The two first round picks and the second were equal to those 4 spots in terms of price. Whereas the price on RGIII(#2) was #6, 1st, 1st, and 2nd.
If you buy a steak from the grocery store(and the steak is worth $10) for $13, you don't say that you gave up $3 for the steak. You gave up $13 for the steak.
Think of it like that. RGIII is a commodity in this sense. And in order to get that commodity, the Redskins had to give us three firsts and a second.