I also have a 182c. It is nice chartplotter but since garmin no longer supports the old style bluechart/mapsource chips, finding chips is really hit or miss. I have been looking for the US inland lake chip on Craigslist and Ebay thinking sooner of later one might show up. The other way to go is buy charts from Garmin on DVDs and try to load them onto blank data cards with a USB data card programmer. (Close to $300 before you even know if it will work).
Adding GPS to my laptop (or iPad) and using OpenCPN is looking better all the time. Does anyone know if garmin charts sold on DVDs are vector or raster formats that can be read on a laptop or are the coded for only garmin products?
Jim