Peter and Gordon,
Thank you for the replies. I have gone with a Lowrance LMS 337C-DF. It is
a leftover model from 2006. It comes with built-in GPS/sonar and also a
separate transom mount transducer (double frequency), external antenna and
various mounting brackets, separate speedometer pickup for the transom. On
sale here in US, being a discontinued model I got it for $545 which seemed
pretty reasonable. (There is little to no difference from this model and
the one that replaced it for 2007 other than an Ethernet port in the newer
model.)

Now as I've begun to learn there are a few things to add, like some SD
portable drives at 2 Gig to download the software update (gotta download it
onto an SD so it can be put into the gps unit so the gps can update its
software). I don't have any 2 gig SD disks lying around so it looks like
that could run a good $60 just to get a blank disk so I can do software
updates on the machine! Then the actual maps/charts for higher res. (of
course for the maps (not charts) you have to buy a proprietary SD disk card
reader designed specifically and only for this software and gps unit just to
transfer the higher res maps/charts from the CD/DVD into the gps unit).
And, finally a power adapter so I can use it in my car. It doesn't seem to
want to end. At any rate, I've taken the leap. And the icing on the cake
is that there's no one at any of the marine shops around here who can demo
any of the units, speak knowledgeably about them, have the high res
maps/charts available to show them etc. Of course once you buy the detailed
maps/charts, if you are unhappy, it's too bad because they ain't takin' them
back!

I looked at several brands, including Garmin, but concluded that they all
pretty much have us over a barrel. There are a lot of after-market
accessories to buy to get it looking like you think it should when you take
it out of the box regardless of which brand I choose.

CB