I found this for a dollar, and although I normally stay away from the K'NEX kits, I bought this one because the parts were still sealed in the original bag.
Normally the K'NEX kits are big and bulky, and half the value of the toy is wasted in shipping costs. If you find the kits for really cheap, it could be a good purchase for a Craigslist flip, or eBay, provided they are in excellent condition, and the closer to Christmas, the better.
Amazon has these new for $13.99 k'Nex Flying fun Set Building Set 112 Pc, so I can't hope for a whole lot out of this auction. I'd give it to my kid if he didn't already have thousands of legos.
KNEX Flying Fun Set 10 different models unopened ends May 30
Update: Sold for $3.24 I've got to stop messing with this nickel & dime crap!