Cork

[warrenss2]

Here is some cork tiles, at a decent price, available in the States.

http://www.lumberliquidators.com/catalog/product.jsp?productId=1588&categoryId=448&sectionId=2&subCategoryId=0

They are not untreated though. But a friend, Scott Larson of Terra Incognita fame (http://nagssociety.com/index.htm) has been using them with good results.