Everything, Dez, because waterproof boots, of a similar style to what you think of as wellies, are also made of leather; oddly enough, just like the boots the Duke of Wellington would have worn, because they didn’t have Vulcanised rubber or plastic or neoprene in the 19th Century.
And this may come as a bit of a shock, but quality is very rarely cheap. If you’re daft enough to walk ten miles or so across country in foul conditions wearing a pair of wellies costing £10 or so, you deserve the blisters you’re almost certain to get.
I have pair of regular type wellies bought for a tenner or so from a builders merchants; great in the garden, or a building site, but out walking? Good God no! They were horribly uncomfortable and left me almost unable to walk back to the car after a couple of miles.
I’m not a mug, as you like to think, I like a bargain as much as anyone, but I’m prepared to pay a reasonable price to avoid ending up weeping in pain.