As a person with actual experience with Grand Design, I got 30% off MSRP and a front bedroom AC installed. GD also worked with me and corrected an issue with my awning three months out of warranty. I had a very nice 30 minute conversation with the VP of customer service. I emailed him about the issue, included my VIN number. He called me back after getting my phone number from their records with the help of the VIN. I don't have any issues with any of the installed equipment and we really enjoy using it. The salesman who told you that was blowing smoke - like some forum posters here. Grand Design isn't the one your dealing with - it's the dealer who already owns the trailer or will own it and can get it a a specific price. If you have a General RV dealer in your vicinity, they are a high volume GD dealership and therefore can be dealt with.
The trick is to not be a buyer on your first visit to the dealership, and have them show you different models and brands. When your ready to deal, pull out your phone and calculate 30 - 35 percent off the MSRP on your phone - or whatever number your comfortable with. I did this and it was significantly lower than the number they put in front of me. I simply showed them my phone and said this is where I'm at - and when they asked if I would be a buyer at that number, we asked for a minute to discuss. When they came back, we told them we would buy at that number if they threw in a front AC with thermostat. They accepted, we bought. You just have to be ready to walk away - they will call you back.
If you are interested in GD, then check out their owners forum
here. You can talk with actual owners of the model your interested in and get the pros and cons from them. Good luck and feel free to PM me.