Purchasing Advice

I have decided to purchase a 2004 Suzuki Aerio SX in the next few weeks. I am looking for advice on how to negotiate the purchase price in Canada. How much actual negotiation room is there from MSRP ... I've read anywhere from $1,500 to 3,000? I have also read about Faxing a few dealers in your area for quotes ... what kind of results have you had in doing this? Any advice/tips would be appreciated. Anything to watch out for here?