The seat blanket situation is a nieche but supply is low, I would pay $140 for good quality. But it sounds like you haven’t experienced enough failure quite yet. If I had a mill I would only cut 2.25 slabs or bigger. The wood movement might not happen until it leaves the state but it will happen eventually. For softwood I would cut 6x6 or bigger lumber and turn the corner pieces into firewood (less work more money) win win. The preferred wood for seats is white pine it’s eastern lumber.