I didn't want to hijack another thread on this... thought it would be easy to answer in the forum though. I'll move info to the wiki, too.

The wiki has a general source list for wood:
http://wiki.techshoprdu.com/index.php?title=Where_to_get_Materials_and_S...

WRT selling 20 b.f., the bigger places are Capital City and Wurth. Klingspor and WoodCraft both have a full supply/variety of all kinds of hardwoods. All 4 will be more than happy to sell you 20 b.f. A single board 8' x 12" x 1" is 8 b.f. These stores have rough and faced lumber in all sorts of sizes, but normally range in 4 - 20 b.f. sizes. They generally will not cut single pieces smaller than a certain remaining b.f. They post their special rules in their lumber areas.

Also, for larger projects (100 bf+), there are a couple locally sawyers in the area with great prices. They can deal in smaller sizes too, but at least one I know is fairly far way (New Hill).... so it may not be as practical. More info can be found on ncwoodworker.net.

1 b.f. = 12" x 12" x 1"
Board Feet = length(in) x width(in) x thickness(in) / 144
or
Board Feet = length(ft) x width(in) x thickness(in) / 12

Easy online calc at: http://www.sawdustandshavings.com/wood_information/board_foot_calculator...

Lumber is usually sold in thicknesses of "quarters"... "4/4" lumber is properly graded, rough-sawn lumber about 1" thick. If it has been surfaced (planed), the thickness will be reduced. Typically, a 4/4 board with 2 sides surfaced (called "S2S") will be about 13/16" thick. ("S4S" means all four sides are surfaced).

Some stores you'll have to measure the board yourself and then see how they measure it... and then come up with a "fair" measurement between the two of you (due to less useable parts... blemishes, nicks, etc.). They are usually fair (i.e., will give you a break). If you're a jerk... they're less likely to give you some "free" wood. :D I believe WoodCraft puts a sitcker on each board with what they measure the board to be... theirs are mostly fully surfaced.

Hope this answers your questions.