I get it locally where I buy hardwoods, highland hardwoods dot com. I can't source good baltic birch locally.
Hopefully, I bought my last two sheets of 3/4" today. When I started this thread a few months ago it was 69.95/sheet. Today, 89.95/sheet. I get 16, 3 1/2 x 60 boards per sheet so it costs me $1.12/foot vs maybe $1.06 for pine but there are no knots or twists.