I buy my wood as boards from a specialty wood supplier - so not "blanks" but boards.
If I wanted I can get 8/4 Curly Maple, either hard (sugar) or soft (red) 2" thick, 8-12" wide by 10 FEET long (could easily accommodate a 96" barrel
.
If one of the stock suppliers can't help you out, look for a specialty wood shop.
You often have to pick through boards looking for the grain direction you want and you do buy way more wood than you need (plus a lot gets wasted), but in the end the cost is often a little to a lot less than from one of the stock suppliers - "because you are doing all the work and dealing with the waste wood".