I've paid for a few endorsements too - but never at the behest of an employer, or potential employer. Nor have I offered to pay for an endorsement to get a job. And certainly not paid to be a co-pilot to gain hours.
Those sorts of things are little more than the company shifting the burden of operating their business onto someone else, but without also passing on reaping the profits. It masks the true cost of operating. You wouldn't expect the office staff to supply the stationery, computers & software and pay the electricity bills, would you?