Major companies like Amazon and eBay didn't get such an inflated reputation because they are "scam sites." eBay is primarily for auctions and they sell no in-house items, so you're more prone to risk over there. The chances of you getting flat out "scammed" are pretty slim unless you just walk right into it.

Amazon is probably the best place to buy anything on the internet, not sure why you'd be suspicious of the site at all. I've been a Prime member for years.