I have a 1999 Volkswagon jetta (new body style) and the fuel pump went on it.?

My question is, can you just change the fuel pump on it which goes for 50-100 on ebay or do I have to change the whole sending unit? I am not sure if autozone is trying to make money but they are telling me it is not like any other car where you can just change the fuel ump only, the whole system has to go. Is that true? I really dont want to pay $300 to buy the whole system.