I just don't take offers till they see the bike...I tell them they may not even want to pay me when they actually see it. Most low ballers wont even show up. THey'll offer you a stupid number and when you accept they'll show up and offer even less. Just stick to your guns with "I'm willing to work on the price but not until you see it." That gets rid of half of your problems.
I very much agree with this. If they are serious about buying the bike, they will be serious about actually taking the time to first take a look at the bike and then actually make an offer should it be lower then the advertised price...
If you are willing to deal with the hassle of selling your bike to a private party, its going to be the best way to go because you can get the most money out of it.
Keep in mind that you'll need to spend a lot of time and energy with dealing with the private sale which is why many just opt to go with the dealer.
If you have a good relationship with the dealer, you'll be able to get a-little more money for your trade but it isn't a huge difference.
Ultimately, you loose either-way on changing your bike so you have to decide how much of a loss are you willing to accept and how much time you're willing to spend on the entire process.
Remember your dealer, like you values their time and wants to make profit off the bike, otherwise they will not be able to pay their bills so be reasonable.
Do your homework, find out how much your bike is worth and hopefully, you'll be able to find the best solution that works for you.