Should I walk away with deal. Mold in basement

Hi
I have put full asking price on the house as I like it very much along with closing cost. Owner is willing to fix it.
Does House deserve full price after fixing, Will I able to resell it easily.
Will it come back etc are questions which I may not know answers at this time
Should I back or stay ?

Found elevated levels in air sample
Aspergillus/Penicillium
outside air sample:
raw count 3
count m3 60
% of total 3.1
Inside air sample basement
raw count289
count m3 12200
% of total 87.5