I think best option is to buy from FLipkart as it allows COD service and u should open the package and check b4 paying money if the courier people doesn't allow it just return the shipping it is our right to look the products for any damage.
Also letsbuy may offer cheap price than any other site they have more negative review like not delivering or taking so much time for delivery etc...
And one another thing about letsbuy they limited COD option to only metropolitan places.
My most trusted online shopping site is ebay and second flipkart i will never buy products from letsbuy as long as our govt cyber division is not strong enough to make them refund our money in trouble.