You should search around on the forums for more information.

Most companies have a big jump in price between there 2nd to top of the line group and their top of the line group because some people want the best and are willing to pay a premium even if the return on the investment is low. The other reason you see a big jump is that typically the wheels and components will also be upgraded between the Ultegra and Dura Ace version of a bike.

I would say, just look at bikes with at least Shimano 105, or Sram Rival(maybe even Apex). Try a few bikes and a few shops out. Search the forums.