I have been to both West Marine and Boater's World re price and availablility of the chips needed. Boater's World appears to have the best prices. To make the trip from Florida to Georgean Bay, I think I need the following chips, MUS 601X, MUS 0004R, MUS 017R, and MUS 019R. The maps and coverage information in the catalogues are a little confusing and the people at the marine stores are not much help. These things are so expensive that I hate to buy one I will not need and I don't want to be caught without one I do need so any advice will be appreciated. Thanks in advance.