要提前解除租房合约，landlord这样charge合理吗？

租房lease还有三个月到期，但因为LD工作的原因要全家回国。今天很friendly地跟landlord（real estate公司）说了，但manager说，如果租不出去，除了剩下两个月的房租，我们还需要付900块钱的罚金，因为lease里面这样说：

Early termination of the lease by default of the Resident, will result in the Resident being responsible for all reasonably incurred expenses, including but not limited to: rent for the duration of the lease term or until a new Resident leases the property, newspaper advertising cost (minimum $80.00 per weekend), a For Rent sign ($55.00), and a leasing fee of six percent of a year\'s rent (minimum $900.00) to find a new resident

觉得很不合理啊，两个月的时间本来就很难租出去，与其多付这900多块钱的罚金，还不如不break lease呢。。。

请达人们给点主意吧。。。谢谢