Where are you buying your Baltic Birch from?

So my local place that I had purchased from closed down.
Need to call around but wanted to inquire where you guys ordered your wood from?
If I could get it precut assume shipping cost reduced.
Looking to get 6-8 full 4x8 sheets. Baltic Birch no filler (I've come across a website selling BB Baltic Birch but looking it it seemed to have filler with outside veneers)

Any other Marine grade plywood or other that is just as good? (density)
These will be tour grade subwoofers (2 at 507Lt box) covered with Duratex or Raptor Liner.