Hi, ok my question is,.. is amazon.com a secure and real website?

ok well the reason why im askin this question is cause im tryin to buy the samsung sch-a990. and when i went to the verizion wireless website, the price on the phone is 299 dollars. and i saw the same phone for a lesser price on amazon.com which is 189 dollars, so im kinda not to sure about this website, since ive never baught anything from this website. so can someone please tell me if this website is secure, and how is it possible for this website to sale this phone soo cheep!!!!!!!!!