Teak lumber has been in vogue for centuries, but thanks to a number of limiting factors (deforestation, trade sanctions, etc.) it's not the easiest building material to locate. It's unlikely that your local lumberyard has teak decking stacked on a pallet, and the world's primary teak forests grow in a nation that's under a US trade embargo (Burma).
Fortunately, forestry experts are cultivating top-quality timber across many of the world's dry tropical regions, e.g. Latin America. Plantation teak is a convenient and eco-friendly choice for those in the market for teak decking or counter tops, because not only is it just as beautiful as Burmese teak, it's usually about half the price.
However, though this sustainable resource is now readily available to builders and designers, only handful of outlets carry the product. Therefore, few architects or designers feel comfortable calling for teak wood in their designs. Hopefully, that won't be the case for long, because a number of tree spacing calculator wholesalers are now offering ecologically responsible plantation teak, you just have to know where to look.
Pacific Coast Teak - Located in Paso Robles, Pacific Coast Teak is an excellent resource for high-quality, eco-friendly teak lumber for those living along the west coast. Boasting a high degree of tree spacing calculator environmental credibility, Pacific Coast Teak is the closest teak lumber source to the continental US, reducing shipping costs and feight emissions. Their website lists contact info, but no prices. Ostensibly, you'll need to contact a representative to get custom pricing for your project.
Proteak Renewable Forestry - With plantations along the Pacific coast of Mexico, Proteak is both a producer and dealer of plantation teak products including cutting boards, counter tops and lumber. One distinguishing characteristic of this company is its environmental record. Not only was Proteak the first FSC-certified company in Mexico, the company protects over 2,000 acres of tropical forests adjacent to its plantations. Proteak offers boards in the following dimensions (in inches): 4x4, 5x4, 6x4, and 8x4. Lengths: 4-10ft.
TeakYard.com - This teak supplier specializes in renewable "slow growth" teak lumber, cultivated without the use of fertilizers or irrigation. This allows their trees to grow at a natural pace that reportedly gives it the look and durability of Burmese teak. Apparently, teak plantations utilize methods that accelerate the growth rate of their trees, altering the characteristics and grain pattern of the wood. Teakyard offers a number of teak board packages, ranging from 20 boardfeet of 4x4 lumber for $300 to 100 boardfeet of 4x4 lumber for $1,400.