[seaslug]

Small repairs are very easy with a simple soldering iron. You may not even need extra plastic. If you do need plastic look inside your yak - you will usually find some place where you can take a shaving or three without hurting anything. Put the tip of the iron on a suspected seam or crack gently and remelt together. If you actually have a hole, feed in a bit of the plastic shavings.

Piranah's suggestion about getting the same color from your same manufacturer is great because different color plastics and plastics from different manufacturers may not work well together. That said, if I was having trouble finding the plastic I would try some regular milk bottle plastic.

You may want to practice on the milk bottle before you go after your Yak!