It's in a buyers eyes. At the initially advertised £55, I'd think, would I buy a set of maybe used/maybe not brake lines that may or may not have been stored in the needed sealed container to avoid dust/grit ingress which will ruin caliper seals fast?
Given brand new, sealed, end capped, known origin new components start at £69, and top out at £109 for pretty coloured jobs, I'd say go for brand new and known. Then if there are issues there is return ability. Buying these, like any second hand part is like buying at a car boot sale, no rights, no returns.
Is it worth the £14 saved?
My opinion, No.