HW components are expensive across the board usually. They don't have to be, the Vex BB controller I mentioned was a second hand affair (as Chris mentioned, they aren't readily available in the UK and are expensive new) and the pair of Ampflow A28-400 motors for my upcoming HW were definitely second hand as well.

I like to think of buying second hand as them having been tested in the sport in some capacity, even if it was only for testing purposes by the seller. As Terry mentions, buying brand new doesn't ensure they'll last any longer than used and as you might imagine, this sport is unforgiving. I've blown up at least one Cytron dual controller which I bought new.