I had to return a chip to a seller in the UK and thought it was going to cost an arm and a leg. Went into the local PO, walked up to the automated machine, told it I wanted to send an odd-sized envelope (padded/bubble, less than 1/4"), it told me to put it on the scale, asked me if it was less than 3/4" (or something like that), and poof, $1.20 was my postage (might have been $1.07, but still...). I was elated and the chip was confirmed as received. Obviously, thickness, weight, and envelope vs. padded envelope vs. box factor in as well.