How to get Golden Trove Carafe 2015

I have purchased 5 Lockless Luckvase 2015 and 1 trove carafe but did not get any rare courier or golden trove carafe so is there any way to get these change or it just a cheap way to spent money as one of my friend opened 60 but did not get any rare but i have read one line while opening case that if i will add signature and if there will be 10 then there is chance to get rare so what is that? Golden trove carafe or anything else?

Second, how some people can sell these Golden trove carafe or items which are tradeable and marketable after few months? I have seen people selling golden trove carafe 2015 in 300+$ but if i try to sell my items then it says you can't sell items beofre nov 2015 then how can they?

Hope i will get good reply so i can save my self spending a lot money. Thank you