If you are able to access the river or lake by car you can step up into a one man or a two man float boat. These will need a trailer or you can strap one to the roof of your car. They are infatable so you can let out the air for easy transportation. You can cover massive distance in a short time in one of these. Think of it like a kayak very fast and quiet.
Here are some pics of the various types of floatcraft that are used by fly fisher men and duck hunters.
A one-man pontoon will cost you a bit more money. Again this is a one man float craft and can be used on larger rivers and more rough waters. You should expect to pay around $600USD for a nice one.
These are a great low cost way to get started fly fishing on a float craft. You can pick these up very cheap for around $200 USD. These are ideal for quiet water ponds, pits, and small lakes