Hi Maria,
In the mailmerge main document, press Alt+F9 to toggle on the field codes
and insert a \# ",$#.00" formatting switch inside the closing } of the
mergefield. Use Alt+F9 again to toggle off the field codes.
Please post any further questions or followup to the newsgroups for the
benefit of others who may be interested. Unsolicited questions forwarded
directly to me will only be answered on a paid consulting basis.
Hope this helps
Doug Robbins - Word MVP