It doesn't make for as good of a headline, but learning to look at solds (and even more importantly, sell through rate) is the first thing you learn (or should learn) if you do any reselling.

Additionally, you have to factor in free shipping. A rough way to do it is to multiply the % times the average shipping price and deduct that from the average sales price (so the "real" average sales price for the totes is closer to $14 or so)