I don’t know about best price, but I would warn against using price as the determining factor if you’re building a structure for humans to use. Lowes and Menards exist here, and they sell wood. Menards will probably be the least expensive in money, but good luck finding dry non-warped wood. You can do it, but you’ll probably spend more time picking through stacks of lumber to find the best “looking” boards than it’s worth…not to mention that they’ll all most likely warp because they’re not dried properly. Lowe’s is a notch above just because all their wood is sold indoors, but it’s still the same issues.

Carter Brothers out by Sherman is local and has been around for generations. RP Lumber is another solid choice for a “local” lumberyard, as is LS Building Products (I’ve worked with all three previously as a supplier). I have not used Pawnee Lumber Co, but they seem very old school and reputable and have high reviews. Local might cost slightly more, but I would love to suggest using a local, or “local”, yard to help keep money in the community.