I usually know what I want when it comes to holsters. Typically, you can find a lower price on-line, vs. buying one in a gun shop. But every once in a while, you can score a good deal on items in a gun shop.
If you want to shop for one in a gun shop, make sure your handgun is empty (leave the mag out) and ask the help inside the store, if you can bring it in, vs. just showing up with it unannounced.
For a while, leather holsters pretty much were it. But now, the kydex holsters tend to be more durable and long-lasting, as well as more low-profile.