I'm just about to embark on my first large woodworking project (some
mission bedroom furniture). I have some plans which include a cutting
list and a materials list like so:


(2) 2x6x96"
(3) 2x6x72"
(3) 2x4x72"
etc.....

What I am confused about is exactly how I take this information and
shop for wood. How do I properly translate this into board feet?* How
can I estimate how much this will cost me?
If I call a mail-order place, will I just order X board feet of a
particular thickness, and just get random widths, or is it like an
actual lumberyard, where I can specify (at least somewhat) the required
lengths and widths.



* OK, I can do the math, but I don't know what assumptions to make.
F'rinstance: A piece of lumber 12"x12"x3/4" is a 1x12x12", but is it
calculated at 1bf or 0.75 bf ?