I have obtained a fixed price bid for some contract development on a project expected to take 4 months. I believe that they have done a very good job of estimating the effort required to deliver the project. The work will be done in a country whose exchange rate has weakened relative to the dollar over the past year.
For example, in Ukraine the exchange rate has ranged from 8.2 to 13.9 Hryvnia to the Dollar in the last 12 months.
The best overview I have seen for contractually dealing with this issue was this CIO article
How do you recommend building a win-win contract that takes currency fluctuation into account?