Replying to I may be in deep shit...

So last March, I bought a new ski jacket, because I was using an Arc'teryx shell that was tech as hell, but had no steeze and was like paper thin, so it wasn't warm.  I never wore it and never took the tags off because my season was already over.  So I put it on a week ago and realize it's WAY too small.  It's a size small, I need a large.  So I list it on NS (check my FS/FT thread, got some other stuff too), and nobody bites.  So I just listed it on eBay, and here's where the shit could hit the fan.

You see, I made the reserve 87 dollars (on a brand new $200 jacket, not bad).  So worst case, I could make only 90 dollars off it.  I need at least $125 for a new jacket.  And I need to buy it before camp, which I leave for in 2 weeks.  My parents are already pissed that I spend what little money I have on new ski stuff (even though the only things I've bought are boots to replace my boots that are 2 SIZES TOO BIG, and a helmet to replace the one that weighs a ton and falls off my head). 

If I tell them that I went over their heads and sold the jacket that I begged them for, and then ask them to chip in for a new jacket (as a gift for owning the shit out of my final exams, which I did), they'll string me up on our chimney and let the crows take me.  So if this jacket does sell, how do I pitch it to them?

They're already extremely hesitant to let me go to camp, and my mom said that if I was even the slightest bit of an asshole about anything she wouldn't let me go.  I need to play this perfectly.  Any suggestions?