For now..I would take a small power head, attatch a piece of flexible tubing (you can get it at the
LFS) and then stick the other end in a garden hose. You should be able to do the entire thing for about 30.00 (or less if you have a hose). Drop the power head in, and plug it in. That could even be a long term solution for you. Anytime it gets full, pull out the "drain system" and lower the level of the pond a little.
I did something really simular to this a few weeks ago. My pond had about 2 feet of water in it and it wasnt finished...had to get it out. I have a pump that runs 2800gph...attatched the hose, stuck the other end into a garden hose and ran it down the gutter. Very easy.