or go shopping and buy everthing you want ---> go shopping for everything you want
But ,can you describle how much is one billion dollars?but 不能放在句首,并且这里也没有转折的意思.建议改成In fact,can you describle.
It is acknowledged that the price of the two...acknowledge（众所周知,为大众所认知）这个词放在这里太大,用来说某种现象或趋势等等,用来说两个手机的价格不合适.
改成 Given that the two new iPhones released in September,2014 cost five hundred dollars,you can buy two million iphones with the one billion dollars.