Live your dream but first do a lot of research. If you can find a pro in your area I think it's well worth the cost. I have see the horror that some supposd pond builders have left. I found a great "Pond Carver" here in NY. He really is a "Carver" vs. just a builder. You can see the results on this web site:
http://frontiernet.net/~catpond/ We had a difficult site that some other "builders" were scared off by. Thank God.... It was a bog area that was very over grown with brush. Quite a challenge but so worth it as you will see by looking at the photo album on the web site.
Good Luck.