I am looking at getting some new electronics with a GPS on it.  I saw the Mark-4 with GPS I love the price and I know some peope will say spend a little more to get a better one, but I just cannot afford to.  My question is I want the built in map that comes with it to have  a the contour lines of the lake.  Not just a grewscale "blob" of the lake.  I know it is grewscale, but I want to know if the Mark-4 built in map will have contour lines that come with it, if not how much do these maps cost to buy.  Thank you

The built in maps don't have contour maps for every lake. You have to check the map chips that work with Lowrance units to see if the lakes you want to fish are on the chip. I have the Fishing Hot Spots Pro chip for mine. It has a LOT more maps than come with the built in and cost $100.  With all the lakes on that chip, there are still a lot of lakes with no contour information.

Ive got the M4 B&W version, very good resolution, can see jig going up n down under the boat, very clear....but no contour lines on the map