A while back, I met one of those Eagle Jet 'FOs' who was paying for the privilege of flying for Royal Air Maroc. He was positively dripping with bitterness at the injustice of it all, but that hadn't stopped him shelling out to hours build in a 737.
To put it very mildly indeed, he didn't come across as someone you'd want to be locked in a flightdeck with for hours on end. Which may explain why he was having to buy his way into a right hand seat - in 2007, at the peak of the job market.
As MP says, there is a world of difference between self-funding a type rating (wrong though that is) and depriving a professional first officer of work by paying to do his job.