You can check Middle Eastern grocery stores (Labanese, Jordanian, Palestanian, Egyptian), they are the most places who carry rose water. You can also check a local health store that would probably have rose water. You could also try to make your own rose water if you want.
Here are the ingredients of rose water:
2-3 quarts fresh roses or rose petals
Ice cubes or crushed ice
Directions for making your own rose water:
1. In the center of a large pot (the speckled blue canning pots are ideal) with an inverted lid (a rounded lid), place a fireplace brick. On top of the brick place the bowl. Put the roses in the pot; add enough flowers to reach the top of the brick. Pour in just enough water to cover the roses. The water should be just above the top of the brick.
2. Place the lid upside down on the pot. Turn on the stove and bring the water to a rolling boil, then lower heat to a slow steady simmer. As soon as the water begins to boil, toss two or three trays of ice cubes (or a bag of ice) on top of the lid.
3. Youíve now created a home still! As the water boils the steam rises, hits the top of the cold lid, and condenses. As it condenses it flows to the center of the lid and drops into the bowl. Every 20 minutes, quickly lift the lid and take out a tablespoon or two of the rose water. Itís time to stop when you have between a pint and a quart of water that smells and tastes strongly like roses.