Not Slovak, Scottish but I have a Slovak Teta.
Audi sell a set of roof bars the part number is 8P0071126B. These are advertised as being for 2003 onwards however I think there is no difference between a 1999/2000 car and a 2003 car body so I would check with them to see if it will fit.
If it does, I think that Thule carrier accessories fit the Audi roof bars.
If this will not fit then I know that Audi definately made roof bars for the A3/S3 before 2003. You might have to check ebay or online somewhere else.