At those price points you would not want to add the price of shifters to the mix. You thought bikes were expensive??? The whole bike is a super value compared to the prices of the individual pieces.

Besides, there's nothing wrong with either Sram or Shimano components. Both are of equal quality along the same price ranges. Furthermore, as new bikers, there is even less reason for you to worry about brands. You wouldn't be able to tell any difference in them.