I would have to agree with the above post 100%. All of the Jessica pins are Disney Auctions, not Disney Shopping, and LE 100 to boot ... and at this point, I believe all very valuable pins (I'm not a Jessica collector so I can't give you estimates on how valuable, sorry). The Stitch pin you want is Disney Shopping and an LE 250. In my honest opinion, you would not be getting a very good trade if you traded any of the Jessicas for that Stitch 1:1 (especially if you considered what you'd have to give up to get the Jessica).
I know how it feels to want a pin so badly you can almost taste it, but there are times when you really should walk away from a potential trade because it really isn't the best time to make it. I do believe you that you want the pin, especially since you are so close to completing your collection - and if I had the Stitch pin, I'd trade it to you - but do you really want to overtrade so drastically to get it?
My best advice for you is to let this particular trade go because you aren't getting a good - and by good, I mean equal and fair - trade out of it ... or negotiate something other than a 1:1 trade (have the other person add something to the Stitch pin for the Jessica). The most important thing to remember is not to be overly hasty in making trades that aren't equal. This other trader could be sensing your desperation and proposing this trade because of it. I firmly believe (and it has worked for me ever since I started pin trading too many years ago) that if you are meant to own a pin, it'll find its way into your pin bag eventually. Sometimes you just need to be a bit more patient than you would like and wait for the right trade opportunity to come along (but given enough time, it will).