cant help you on the price, but you can help yourself by researching what you want done, and specifiying what the contractors are bidding on so when you get all your numbers you can compare apples to apples.
know what kind of cbu you want and how it needs to be installed and spec that for the estimate
know what tiles, their size, and pattern and spec that for the estimate
if you want the grout sealed spec that
waterproofing anywhere spec it
figure out your sqft, and add 15-20% and spec that for the amount of tile
once you do your home work and know what you want, where you want it get your bids, then when one comes in higher ask the contractor why they charge more?
if you spec the bid out so the contractor isnt adding extra stuff or leaving out steps that should level the feild quite a bit. and then you know the bids you are comparing are for the same work, and not someone who is 2grand cheaper but is doing shoddy work
brad