Robert if you're just wanting a GPS-Graph, the Lowrance HDS 7 Elite looks like a good option. Much cheaper than the HDS Gen2's, but I believe you're giving up sidescan. The sidescan would be very advantageous for lake mapping.
Once I get all my lake have-to's done the Spring, I think I'll go with an eBayed HDS Gen1 Lowrance and DrDepth. I can see a local market for mapping with gallery wraps, laminated maps, etc. Just have to decide if the effort warrants the expense.
As far as convincing your wife, good luck. I've had mixed results with the same issue.
