I just want to get the right number format here in germany, so i need to show commas as decimal separator instead of points. But this...
DECLARE @euros money
Well, as far as I know, there are no culture-specific options for convert available.
So you can do it using replaces (yes, it looks a bit ugly...)
select
replace(replace(replace(convert(varchar(30), @euros, 1), ',', '|'), '.', ','), '|', '.')
Idea: first change comma to something, then change dot to comma, and then "something" back to dot.