A shofar is used to perform the Jewish call to worship. This instrument is traditionally made of a hollowed ram's horn. When shopping around for a shofar you should consider what you want in terms of the look, feel, and ease of use of the shofar. Some shofars are beautiful but are very, very difficult to blow. Others are simple to blow but are very plain.
The internet is a great place to look to compare a wide variety of shofars from the comfort of your home. A quick search with any internet search engine should yield several results, consisting of several online stores selling shofars. This is a good way to find out what you like in terms of the aesthetic appeal of a shofar. Some people like very dark shofars and others prefer them to be very light in color. Some people like straight shofars and others find those with several curls more appealing. Looking through your options will likely give you some ideas of what to look for when you go shopping.
After searching the internet, it is a good idea to go to your synagogue's store. Most synagogues have an active sisterhood or brotherhood which will sponsor a store for the synagogue. This is the perfect place to touch some shofars to see which textures you like best. Some people find very small shofars exceedingly difficult to hold whereas other people have the exact opposite opinion. This is something that you simply won't know about until you physically hold the shofar.
Now that you know what you want your shofar to look and feel like, try blowing a variety of shofars. You will quickly learn that shofars, unlike musical instruments, do not all work with ease. Some will make you feel like you are going to pass out before you can get them to make any sound. Others will be easy to blow, but will have sounds that you do not find appealing. This, again, is something that cannot be found on the internet. You will actually have to try out several shofars to find what's best for you. It is highly suggested that you sample several of these instruments before you buy a shofar, since shofars can rarely be returned due to the nature of their use.
Shop around for your shofar. Your synagogue's congregation members should be able to point you to the direction of lots of shops that stock all kinds of Judaic material.