I would want to know EXACTLY what they plan on doing for $300.
Oil = $30-$40 (retail)
Filter = $15 (retail)
I am sure they will charge you 1hr of labor, which will probably be $60 or so. So that takes you to $105-$115, including the hour or labor.
What else are they going to do? Adjust the chain? That is another 5min worth of work.
Personally, I have never had a dealership do a first service on any of my bikes. I do it myself. I actually do the first oil change at about 50 miles (hard break-in, where I stage RPM's up, utilize a lot of engine braking and perform a few oil/filter changes as I work my way up to 200 miles on the odometer, when I run it to redline).
Unless that first service comes with an oil/filter change, chain adjustment, new air filter and a new set of tires, there is no way they should be charging $300+.