Does anyone have an affordable, relatively easy method for constructing a dock with water in pond?
Maybe.
The easiest method that I've used to put a dock on a BOW that has a relatively constant water level is this:
Wait until the ice is strong enough to support a few people walking on it in the same area. Drill holes thru the ice and install 2" Galvanized pipe in the BOW. Attach brackets to the vertical pipe that allows horizontal pipes to be attached. Rest the joists on the horizontal pipes and build the dock.
This dock is 68' long.....
If the BOW has fluctuating water levels, go to
http://www.dockbuilders.com/ and buy all the floats and hardware from them. They will also help you with the design of the dock. Buy the treated lumber locally.
A number of people have used plastic 55 gallon barrels for flotation instead of the floats that dockbuilders supply. But, that takes more work on your part in regards to engineering and design of the dock. You have to figure out how many to use for flotation, how to build the dock frame, etc.