How much would this site cost to essentially duplicate for me that like the design: http://www.contractoruk.com/
I think that 400 $ is minimal price. Graphical design is simple, but customize cms for your needs not so easy. 400$ and more.
I am sure that you can find someone who will do it for you for 400$. But 600-700 $ is standard prices.
The thing is there's not really a true standard as far as price for these things. So the only person whom can give you a certain final price is the designer that you hire to do the job. Even then, if the designer just charges by the hour, the best they can do is give you an estimate. Beyond that the best you are going to get is a range of prices, such as the ones the other people replying are giving you.