Bannetons, or rising baskets, are available from many sources. Many specialty houses have them at prices starting at $20.00 each and going up from there. If you are in the USA, and near a Cost Plus Import house, Cost Plus usually has them for around $5.00. The liners are a bit weak. If you wash them, let them air dry, don't dry them in a dryer.
The bannetons help shape the loaves, and leave a nice wicker pattern on them. The liner helps wick away moisture, which helps form a better crust. To prevent sticking, make sure you flour the liner.
The nice wicker patterns tend to be stronger before the dough is baked. 
Oven 
spring usually wipes out the pattern. However, if the dough was pretty much at its full rise, the pattern can remain. Here's a loaf of Pain au Levain ready to go into the oven, and a loaf of Bohemian Rye that has been baked.
In addition to bannetons, otherforms are used. The Germans use an unlined cane basket they call a brotform, or bread form.