The best place to buy statues are at pilgrimage sites. Then it will be imbued with all the holy energy and blessings from the area. I think this is much more useful than buying from a random store. Temples at very famous statues sometimes have replicas of the statue, which is another level of awesome, because this can help to regenerate the feelings experienced from the main statue whenever looking at the replica you purchased. Very old and very famous statues are excellent because both have an accumulation of the devotion of what is often millions upon millions of people. This is of course a lot easier to find in old Buddhist countries like Nepal, Indian and Japan, than Western counties like America, but there are still some. The Great Buddha in Kamakura and the Ushkin Buddha (both in Japan) are great examples of places that sell beautiful replicas. (sorry that all I know because I live in Japan). If you can't buy at a holy site like that, you can get whatever statue you like on ebay or whatever, but be sure to bring the statue to your most respected teacher and ask them to bless it for you. Then you'll be able to take your teacher with you wherever you go.