You'll have to deal with 2nd hand shops which sell used equipment. Those that retail brand new items don't do trade ins unless you're willing to offer your set at a ridiculously low price ... ie $600 for 20D.
Anyway if you trade in yr 20D for a 30D at a shop, be prepared to top up a lot of money. A bit is a gross understatement. Why?
The retail price of a 30D at shops is a lot higher than some sources.
The price they'll offer for yr 20D is a lot lower than what its worth.
As the previous poster said, gd luck man. :sweat:
You'll need it.