I'll take you at your word (forgive the skepticism but this is the internet ). Anyways, Shimano seems to have truly broken through with electronic shifting. The Di2 group is something like $3K but since it seems to work really well it is becoming more and more used, both on pro bikes and on bikes for people who are willing to drop serious money ($5K+) on their bikes.

I'd guess the pro time trial bikes are the most expensive since the top ones come out after alot of time in wind tunnels and they use the Di2 if they can since the electronic shifting seems to be especially nice on a TT bike.

The most expensive bikes won't be in the TdF. Those are the ones from custom builders like Vanilla and Richard Sachs. Big $ and 3+ year waiting lists but not TdF bikes.

Btw I closed your thread in single speeds. You won't get anything there.