IF the dealer did the new bike prep that both Harley and most customers pay them for, the 1000 mile service is basically a fluid change and belt adjustment. Even at full retail prices for the filter and fluids, and an hour of labor, it's not close to being worth the $300 to $500 most dealerships charge. This is basically just another extra dealer profit item, and there is no valid reason other than greed to even have this service requirement. Did your car have a 1000 mile service requirement? No it didn't.
If you are a hands-on type with some basic skills, there is no reason you shouldn't do the service yourself. Keep the receipts for any parts and fluids, and document what you did and when you did it. If you aren't a hands-on guy, find a good local independent shop and see what they'll charge to do the service. I'm guessing most will charge less than half what your dealer charges. And don't fall for the BS that some will try to tell you about having to have the dealer do the service to maintain your warranty. That is patently false, as detailed in Federal warranty law.
Jerry