These days you can buy practically anything online, including curtains and drapes. Not only are there a great may retailers on the web which sell nothing but curtains, the prices tend to be much lower than what local shops charge.
When buying curtains online, be sure that you have measured your windows correctly. This may sound like an obvious thing to do, but there are many people who order curtains online and whom receive their curtains in the mail only to find out that they are too long, short, narrow or wide. So get that measuring tape out and ask someone to help you measure to be sure you get it right the first time out.
Many online stores which specialize in curtains and drapes will send swatches of sample materials in the mail. If you are unsure about which curtains to buy from a site, by all means order a couple of samples so you can see and touch the material to determine whether or not you wish to buy curtains made with it. If you have unusually shaped windows you can still buy curtains online as many stores will custom made them for you so that they fit your out-of-the-ordinary windows.