ODB2

Hi all,

I am about to purchace a 97 Miata Limited Edition which has been
sitting in a garage for some time. Seller has to smog and register it
before sale.. well... it passed the smog test but the ODB2 computer
failed ???
Seller claims it failed because he recently gave it a new battery and
it needs to be driven a while before the ODB2 computer comes back up -
is this just a minor issue or should stay away from this one ?

Another factor: it has 97K miles on it and he's asking $4K is that
reasonable ??

Thanks for any answers
/Rene