You may think Bitcoin will be here for a long time but difficulty always rises with new asics getting produced and you may will not be able to reach your ROI when Bitmain announces their new s11 or s10 miner so at the end if you don't mind losing money and just want to hobby mine then go on buy from amazon.I forget to add one thing if you want to know when new batch of miners will be avaible follow Bitmain's twitter they announce when they have a new batch.
you are right but S9 been here for over a year now
Thanks for the responses guys. I decided to go order from bitmain itself even if the expected delivery date is still Jan 2018.
I computed and it would be the same as ordering from Amazon because the amount i saved in purchasing from bitcoin would then be the same as if i already bought from Amazon and I already started mining today. This makes buying from bitmain better because at least you are insured that the product is new and still has warranty.