Charging for endorsements is rubbish. So is salary sacrifice. IMHO any employer that employs you, employs you for the skills/training that you currently have. If extra skills/training are required for your role, then your employer should be responsible for
providing that training, not making you pay for it. However, i cant say that i dont agree with bonding. If you are lucky enough to get into a position that provides your training but bonds you, then i dont see any harm in them expecting a reasonable return of service.