Input text relevant to another cell

Hello,

I am running a small Spreadsheet, now where the problem lies is this:

I have a column called 'project' and column called 'Cost' -

Within the column called 'project' - i am running Data validation with drop down so they can select from a list

In the column called 'cost' i need a formula that inputs a certain cost relevant to what is dropped down from the project column..

Hope this makes sense!

Thanks

Kris