Try the polybond jay....but make sure to read the directions and clean the area with rubbing alcohol prior to applying it. Buddy of mine fixed a 4 inch gash in his canoe with the stuff. Good luck and Tight Lines !

Go with a pro repair.  Look up Mark Cumnock in Chattanooga.  My understanding is most of his repairs are $50-75, about they same as you getting a low end welder yourself and experimenting except his will be done right the first time.  Trust me welding is easy to do correctly.  Pretty much nothing sticks to poly long term, except for more poly that is been welded.

Well I took a propane torch with a heat spreader to the yak. I cut out 2 one inch sections around the cockpit rim so i had 2 little rectangles of plastic to work with. I melted the 1st piece (quite nervously I might add) over the hole. After I got done with that, I felt a lot more comfortable with it. So the next day I melted the other piece over it, using a hot knife to spread the edges out and a big socket like a mini rolling pin. There were no spots where I could pry the plastic up so I would say the pieces are now one and the same. The final coat I melted about 3 times to make sure it was good.
 
I ordered a paddle so hopefully next weekend I am going to put it in Lake Julian just to make sure the leak is fixed before I go planning any float trips.
 
I will post some pics of the repair when I take out the kayak next time. It's all wrapped up and put away right now. Wish me luck fellas!
 
JS