Try your local Suzuki dealership. Since the 1999 model was mechanically the same as the 2004 model, you can only find factory parts at the dealership. I tried multiple OEM/Aftermarket sources for a carb rebuild kit for my 99 Marauder 805 without any luck. Fortunately, the Suzuki dealership had a schematic of the carborator available on it´s website, with each and every little part was numbered, priced and availability is shown. It was pretty cool, since I could then purchase only the o-rings and bowl gaskets I needed to fix the carbs, rather than buying an OEM kit with everything I need and don´t need. Problem is, since the Suzuki dealers know they are the only source for factory-grade parts, they make you pay. A single, tiny, 4mm o-ring cost $5.99, and you have to buy 2 of everything, since there are 2 carbs. You´ll also notice that the air filters cannot be replaced without taking the tank off. My old Kawasaki had the filters on each side of the engine, making it easy to change them.
Beyond the mechanical and back-assward engineering, the bike as a whole is a great metric cruiser. Once it gets older, parts will begin to become available from other sources and the prices should fall with the competition. You should enjoy it, but you will want to move up to 1000+cc engine before too long.