Ebay, for all it's perceived faults, has been an absolute boon to home woodworkers (and many others).
Back in the 'good old days' before the internet was a thing, if you wanted good second hand or vintage tools you had far fewer options. You could attend auctions (occasional specialist, or local general), you could trawl the local junk shops, you could travel to the few specialist tool dealers, you could try word of mouth and see what emerged (rubbish, mostly), or you could await Bristol Design's next tool list, issued by post about six times a year, and hope that if there was something you wanted, your 'phone call to reserve the item beat everybody else. Mine usually didn't.
Now, you can relax in your armchair, and at a time of your choosing, scan through thousands of offerings. Sure, some will be dodgy, but it's usually fairly clear from the listing and description which are naff and which are more genuine. Yes, descriptions vary a lot in quality - I've lost count of the number of wooden bench planes described as 'block plane' - but at least you can look at the photo and make a judgement. Is this a shyster, or someone with no woodworking knowledge offering, in good faith, the old plane they found in grandad's shed? And if the price is right, is it worth a punt? Your call - but don't blame the seller if said jack plane turns out to be third quality rather than Marples Shamrock brand.
Really - it's a golden age for finding used gear. But one thing hasn't changed - used gear is used, and you take a risk when you buy used rather than brand, spanking new with guarantee and legal rights. Your choice, but don't cry foul when used turns out to be not quite as pristine as brand new.