Volkswagen offered two automatic transmissions in 2004:
01m 4-speed automatic
09a 5-speed automatic
Depending on which engine your vehicle has will dictate which transmission you have.
The 01M uses VW p/n G 052 162 A2. For a suitable replacement to this part number look for a fluid that meets Esso LT71141. These are actually quite common.
The 09A uses VW p/n G 052 990 A2. This fluid is much more specific to application and you will need to find products that meet this part number. They are available on-line but no OTC oils from the local parts stores/Wal-Mart are going to meet this requirement. Check with local dealership or on-line. I know that febi/Bilstein makes a suitable replacement but whether it's a better deal than the dealership is anybody's guess.
FWD VWs use either a VW, Aisin(Toyota) or Jatco(Nissan/Mitsu/Mazda/Subaru) tranny. If you have the Aisin one, T-IV or WS can be used.
If it's the 09A, VW says it's from Jatco but I'm not sure if Nissan Matic J/K fluids or the equivalent can be used: http://www.volkspage.net/technik/ssp/ssp/SSP_232.pdf
Ever consider getting a ATF change kit from a German car specialist? They can get you the right fluid, filter, and gasket as a combo and save you some money. Also, some VW transmissions don't use a dipstick, and filling the transmission requires a special tool. Blauparts really helped me out in getting special transmission fluid at a low price. Typically Blauparts sells a Ravenol oil that is a perfect match for the OEM fluid, whatever fluid that may be.