@Dannydyn: as you've read, 11-speed doesn't offer a "faster" high gear than 10-speed (and so on?).

You would pay ~$380+ for a Shimano 105 "5800" set of components plus whatever you'd need to pay to have an 11-speed rear wheel plus installation. What you'd get on the rear cassette is one more gear choice in the middle. (There are other differences; (almost) everyone is enthusiastic about 5800. But 5800 does not give you a higher gear.)

Two comparable options:
With a Shimano 105 5700 cassette, you can get 11-12-13-14-15-17-19-21-24-28.
With a Shimano 105 5800 cassette, you can get 11-12-13-14-15-17-19-21-23-25-28.