There are many different places you can shop for parts for ceiling fans, such as Lowe's, Home Depot and Ace Hardware. Each of these stores carries a large selection of parts, and it's advisable to check their online sites for prices, inventory and local availability.
When buying replacement parts for a ceiling fan, it is important to know the model number of the fan. If a ceiling fan downrod, a part which is offered for sale by both Lowe's and Home Depot, needs replacement, not just any brand can work. Downrods are manufacturer specific, and if one buys from the wrong manufacturer, the downrod can't fit into the fan. This is true for almost any replacement fan part. If in doubt, one should ask a store representative.
Another part that often needs replacement is the ceiling fan blades. These are typically sold in packs of five, along with their holders. However, both Lowe's and Home Depot sell a limited choice of single blades.
Ceiling fan lights are commonly replaced, but just because it says it's universal, doesn't mean it actually is. Both stores offer a variety of lights ranging from functional to highly decorative.
Ace Hardware offers a wide variety of pull chains, a part that is commonly in need of replacement. The store offers chains with knobs that range from pewter to wooden, to a nickel four-leaf clover.