Actually cousin family members all have Moto G versions so he is avoiding Moto G.
My experience with Flipkart & Amazon have been good i.e bought quite a few things including mobiles from both the website & all received in time & correct product with no damage or defective products.
On Flipkart - I only buy from Flipkart Advantage sellers.
And on Amazon - I only buy from Amazon Fulfilled sellers.
By the way, sometimes there are good exchange on online sites i.e exchange old mobile phones.
I have previously exchanged 2 mobile phones. At that time I didn't knew much & only restored phones to factory settings & exchanged.
Any info what to do exchanging/selling phones so that personal info, etc... are not recoverable?