Followup:
The $1800 was from a lumber yard for 2x10s in white oak, kiln dried. Kiln drying white oak takes much longer than other species to keep it from internal checking. 1x material was much cheaper. The local sawmill doesn't have a kiln and just sells green lumber, in fact, when asked if it was a stock item, they said they'd cut it when the order was placed.
Should I space the yellow pine solid or leave a small gap between the boards? Tight against each other would look the best, but I'm not sure if that would be the best approach.
Thanks for all the replies.
Scott