Paul - the
My name is Ozymandias, King of Kings; Look on my Works, ye Mighty, and despair!
...and the Eye of Sauron the Terrible few could endure.
Open up your collection and click on Filters ». Next to Trade change the box to Yes. Click Apply Filters at the bottom. This will display the For Trade games.
You can't download this as a .csv file, however you can highlight the information with your mouse, cut, and paste it into a spreadsheet. You will probably want to use Columns » to only display the minimum information you need.
Worked fine thanks. Sometimes you forget the easy solution.