Could it be a scam or is this acceptable?

I sent an enquiry to someone from craigslist with my dates and he confirmed a price of $100 a night for three nights, but I\'d need to pay $600 security deposit and half the stay, so $750 to reserve. Seen as I\'m paying in New Zealand $ that is VERY steep, and somehow with 3 months before the trip I don\'t understand why we can\'t pay the security dep on arrival and picking up the key? I would be happy to pay the full stay in advance therefore if something happened and we didn\'t show he\'d still get his money, but an extra $600? is this normal? not all listings have this, even if it was a hotel or a business renting apts asking for that I\'d be suspicious. I don\'t know this person, just some guy off craigslist, he could be anyone, he might not even show with the key, or worse we might stay and then he finds a way to not refund the money, we\'ll be catching an international flight the day we leave therefore there\'s not much we can do if we don\'t get our $600 back.
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