How much do you pay to take a Taekwondo grading?

I recently met two Taekwondo students from the north of England. The subject of the cost of taking gradings in TKD cropped up and they told me at their club a KUP grade cost £45. On top of that, failing to pass the grading would result in having to pay the grading fee again.

By comparison, at my club a KUP grade test is £15. If you fail it, you can re-take it at no further cost. I don't know what our instructor charges for Hapkido gradings (another Korean Martial Art he teaches) but would be surprised if there was any difference.

The two Northerners told me they had achieved First KUP grade (red belt/black tag) in three years with their club - that'll be a topic for another post later...

So how much is the "right" amount to pay for a martial arts grading? Should it be dependant on what the club needs to charge in order to stay operational? A quick glance at the BTCB website didn't offer any kind of guide, but I'd say £45 sounds expensive.