Look, I do not think there is any hard and fast rule, it all depends on what you find and your negotiating skills. Yes, I do think if you prepay the 6 months you can get 10-15% off and what that starting point is depends on your skills. A friend of mine told someone they had 12 apartments to see and would make up their mind in a couple of days, he called the next day and made an offer take it or leave it and they took it. I think the problem is the negotiating position, many expats feel that because they are in a different country and they are just learning the culture etc they are at the mercy of the other side, that is not true, you can always walk away and there are tons of places available, just have to make the right offers and be prepared to walk. That is all, the economy is getting more difficult and people want the security of dollars now, so I actually think it is a great time to negotiate. There is a lot available in the city, you just have to work it, there are lots advertised in local papers, work it and you will be fine. I always believe you can do and I always do what I want so I think it is a matter of working to find the right deal. There are those that always think they cannot or it cannot be done, I always say " if you think you cannot do it, you are right"
good luck, just dig in and you will be fine
