Been using eBay for years now. Never had a problem throughout hundreds of transactions. Just use common sense and check out feedback ratings - don't buy if the feedback is less than 97%. As with all walks of life, you get bad apples in every barrel. There is no perfect system to beat the outright scum in many systems. I think eBay & Paypal work well on the whole. What about the banks? If someone clones your card details, usually neither they or the police want to know ( they will usually blame you ). This is otherwise known as "The Cop Out" method.
I don't understand the one about £50 value item selling for £1,500. If the other top bids were around £50, and the Nigerian's bid £1,500 as their max bid, the auction would end at somewhere just above £50, nowhere near £1,500.
You can specify where you are willing to accept bids from, mostly stick to U.K - less hastle. Certainly not to Nigeria, scam capital of the world. Who has not received an eMail telling of a Nigerian government minister who wants to give you millions of pounds in return for your banking details. Yeah Right!!!
Just keep your wits about you and you should be ok. & remember the something for nothing scenario, if it looks too good to be true, it probably is!!
Jim