According to the WWWJDIC, the verbal suffix まい can mean:
(1) probably isn't (doesn't, won't, etc.)
(2) don't (doesn't) intend to; intend not to
(3) must not; (when used in an imperative sentence) don't
but I've found this sentence in my 日本語能力試験文法問題対策一級 text:
何であれ, 必要ならば買わなければなる まい 。
Which is the right translation? Or are there other possible translations?
a) 'No matter what, if it's necessary, I'll probably have to buy it.'
b) 'No matter what, if it's necessary, I won't probably have to buy it.'
If it's b), it doesn't make much sense, does it? If it's a), it contradicts the meaning given by the dictionary.