You say you want to try electric propulsion or maybe your gas powered outboard died and you are tired of getting it repaired. Don't head to the marine store. Head over to the nearest Home Depot or lumber yard and build your own like this fellow did:
Though you might want to carry a few spare batteries with you and make sure you have a set of oars as backup. I don't think it would perform like a Torqeedo or an Electric Paddle in terms of efficency but, it might work for your needs and looks like a fun project.