So Can Amazon do it? The short answer is the can but its not likely.
Can Amazon Do It?
Amazon has been funneling so much of its revenues back into growing the business that it actually has negative earnings. Negative earnings with $61 billion in revenues in 2012.
Amazon could definitely do it, although it would most likely have to finance the deal. Assuming it paid a 25% premium, which would work out to ~$22 per share. This would puts Barnes & Nobles market cap at ~1.25 billion, which Amazon could easily do. Just to put it in perspective, Amazon could buy Barnes & Noble, all of its stores and real estate and assets, for 2% of its 2012 revenue. Is it likely to happen? No. But I do think that it would help Amazon in the long run, as strange as that sounds given that Amazon basically put the brick and mortar bookseller out of business.
While I think it would be a fantastic idea for Amazon, it is unlikely to happen for several reasons. The biggest obstacle would be Microsoft's involvement with the Nook. Now I honestly have no idea what the status of that is now that Barnes and Noble is Nook-less, but I doubt that it would let it happen if it has any stake at all in the company.