I'm looking for a smaller 4-5" color GPS that has depth contouring and something more than some dots to designate channels. Anyone have some suggestions?

garmin 276c or newer model.

garmin 498c

Where do you mount the transducer for this?

http://cgi.ebay.com/GARMIN-GPSMAP-29...QQcmdZViewItem

You don't. This is a nice portable unit that does not need to be hardwired. It has a built in stubby antenna, and is rechargable. Just 1 screw and take it home to recharge.
Here is a pic of it on my old boat.
Also can use it in the car.

so the 276c has detailed channels? How does it get the water depth if there is no transducer? Sorry for the newby questions.

i'm pretty sure it showed detailed channels. Looks like the screens of bigger units. Go to a westmarine... should be there.
I bought mine here:
http://www.consumersmarine.com/
You should be able to call and talk to someone there.

Depth is the mean low tide. that should keep you out of trouble.

here's a better pic of the unit.

Try the Garmin 440. Has a ton of detail built in, no need to buy extra chips.

this is what i'm trying to figure out. All i can see are red and green cans everywhere but no "lines" defining what red and what green make up the channel. You wouldnt know what green and red to go within. Hope that makes sense.