It is probably because there is money in business from the entry fee that you need to cover to purchase it. In example, this business is worth $345000, but it has, say, $10000 more inside from the entry fee, so you need total $355000 to cover the whole value. Just ask someone to loan you temporarily until you buy it, then withdraw the cash and pay it back. And, yes, you need money in bank to purchase properties, since people waited for their stuff to get revalued to get extra cash in hand while they had minus cash in bank.