Huh

?
SoftHut has complete "new" A4000Ts in stock (and at a price not so bad when one counts in the non-value of the $), so why go hunting for parts ?
But don't forget they are all NewOldStock, read made in 1996 and never been sold, but that would also apply for any "new" mobo you might get offered.
Unless offcourse you take in MiniMig and maybe Natami, the only real new Amigas since 1996.