There is generally 2 kinds of teak on the market. The old growth that is red and looks like mahogany and is very heavy and ran about $28/board foot about 10 years ago and there is the much lesser expensive grade that is more yellow in color and light in weight. That's the kind that appears on the market as cheap lawn furniture. Whichever you choose, you will have to put a hard finish on it if it will be in or near the shower. Otherwise, the pores will fill with soap scum and fungus.
Prices vary greatly from area to area and year to year.
Tony B Retired woodworker, among other things.
"Strive for excellence and settle for completion" Tony B