I'm not exactly sure what to make make of this, as I'm newer, and I'm guessing it sort of depends, as there aren't really any people selling it on backpack.tf or TF2 Outpost, and the only guy I could find actually selling it on Bazzaar.tf had something else with it, and could only be selling it as a set.

This is the trade (I planed on calculating it, but realized that it was in one trade):

http://imgur.com/vjvf81b

A problem is that it is difficult for the price to stand, as since you were the only seller (If you were selling it like you say you were) then now that you did sell it, now there isn't anyone selling it at 20.88 ref since yours is gone now.

Like you said in your explanation, More proof/counter proof/feedback/constructive criticism is always appreciated, and like I said earlier, I'm kind of new to this so that would be really helpful.