You can enter a list of sizes into the lumber order form on the page for the wood you want to buy.
Look for the "Order by Size" link by the quantity entry box. Ths will give you a form to enter as many sizes and pieces as you want, and will do the calculation for board feet automatically.
Then you choose to either have us select lumber to. give you more than enough to cut your sizes, or have us custom cut each of your sizes. Labor fee will display in your cart.