Yes the cost of the ProEdge is steep. It's worth noting that you could probably buy a cheap linisher and make your own jigs to get yourself a pro edge and also that there's nothing actually wrong with the grinder, many use them, including pretty much all pro's.
The ProEdge is all about simplicity and as such, you pay for it. You won't ever have problems with a diminishing wheel slowly altering the grind of your tools and your bevel will be flat, not concave. I'm not suggesting these things are better than the grinder, just pointing out the differences.