Da bomb prices

I'm the guy who made the post asking about da bomb earlier today, I've decided to go with da bomb beyond insanity because I think Ground zero and final answer might be too much for me, but why are the prices so different on the internet? I am not in the US and I was looking at it on amazon and it costs about 40 bucks, but another site is selling it for 15? Would I be getting scammed with the 15 euros one (the site is called ubuy)?