What lee said. I was just looking at the parts fiche at hdlparts.com, a new reservoir is 14.35. A complete master cylinder asm is 41.18, the piston kit is 28.17.
What exactly is the problem? Is it poor braking? brake fade etc. Did the dealer happen to find this problem while doing something else? It sounds like the dealer has his profit at heart more than your bike.
A tip for you red heat, if you put your location in your profile, you can often find people willing to come over and give you a hand.
The best place to post these type of questions is on the tech board as most of the guys there know their stuff pretty good

. If you wanted to do this repair yourself that would be a good place to ask.
Hope this helps you. Ride safe.