I want to buy a Blackberry Classic. I found a quite good phone on internet. A person wants to sell it but the problem is that he didn't guarantee anything. He is selling the phone in a quite low price. He paid for mobile £250 (and he showed the receipt) and now he is selling the phone with £150. He said that the warranty expires in 8 month which is quite a lot time. Should i take a risk and buy it ? Or better i choose safe method?