I guess it depends on a lot of things:
1) Your ability and skill as a negotiator.
2) The dealers willingness to sell
3) The item you purchasing. (hot item or slow mover)
So for example you want a GPS/Fishfinder combo. Do your home work. What's out there? Furuno 1850 DF combo unit, Lowrance LCX-15MT combo, Lowrance LMS-350-A , Garmin 168, Garmin 188C, and I'm sure a whole lot more by Hummingbird, etc.
I try to look around locally and check out as many units as I can and check all the features. Post a Question here on a unit and see who has it and the replies you get.
OK. I made my choice: I want a Garmin 188C GPS and Fish Finder combo with the Transom mount dual frequency transducer with temp. Now I price it out, trying to compare apples to apples: http://www.onlinemarine.com:
$1,139.00, GPS Discount, Inc. - Scott Farris $1129, www.consumersmarine.com:
BoatFix.com: $1,175.19, Boater World $1,254.99, /www.thegpsstore: $1195.00, http://www.gpssignal.com/$1300.00 , Three river Marine (TRME): $1200,
dbmarine.com/garmin dbmarine.com: $1,123.19
Now I go to the show. I know what I want, and what I be willing to pay for a local dealer.
I am in a similar situation, if you haven't guessed. This is how I am approaching it. I have done the same thing for a VHF and Antenna for the VHF.
My boat is a 17 foot Proline. So space is a consideration. You may have a bigger boat and also need Radar. In which case you can make a package deal for everything. I plan to install it myself. If you want installation that also becomes part of the negotiation.
So to go back to your original question, I guess my recommendation would be to do your homework BEFORE you go to the show. Shop around and gather info and prices. Then go to the show. You can them make a well thought out decision. Hope this helps