ebaY has been getting some crazy bidders of late.
this 15" x20" piece just went for over $140 shipped !
you can probably save money by getting a bundle of
smaller pieces and making a large arrangement out of
them, instead of getting one honk-in centerpiece.
you'll also save on shipping that way as well.
keep in mind that once you grow in enough plants,
you way end up removing your wood altogether to
make more plant-able space. I tried all kinds of wood,
and now keep it all dry on a shelf to keep all the room
in the tank for my two dozen different plant species.