Many of the people who have this problem on toy websites end up offering what amounts to free storage or something similar. They are then surprised when "bots" come to "DDoS" them. These bills are as much a product economics problem as a technical one.
That would make you one of the most successful websites on the internet, or the target of a DDoS -- which was it? I assume you're not saying that "bots" would randomly hit a single, brand-new "hello world" site enough to generate that kind of bill.