Looks like it was so expensive because the treatment was US specifically. Hence the extortionate cost

Also, the kid can walk again!

Source

Notable quotes

And now, nearly two years later, Brecon can walk – thanks to Dan’s selfless gift.

“I’d had 22 years of walking before my accident whereas Brecon had never known what it was like even for 22 seconds,” said Dan, 27,

the family was unable to get the operation done on the NHS where they lived so in June 2013 they launched a fundraising appeal in their local paper to raise £60,000 to travel to the US.

I hope he came up with the 40k dollars for his own surgery quite quickly after that. Perhaps he even got a donation himself considering this news story.