$500k? There entire helicopters you can just buy outright for less money than that. Does the $500k ride come with the helicopter itself included in the purchase?
Uh, a new Bell 407 is north of $4 million and that's before it's equipped for medical flights. You aren't buying one of these for $500k used, at least not one that's air worthy. Eurocopter EC135 are a bit cheaper, but not by much.
I do vaguely remember seeing some bills with such figures. I've been literally developing various OCR and medical coding crap to process the cases and I've seen plenty of real cases. Some cases had eye-popping bills attached, yes.
The $500K spike was some sort of a highway accident response, can't recall any additional details apart from some serious head/brain trauma.
Keep in mind that everything gets significantly inflated, x2 multiplier is guaranteed, x5 is likely, x10 is not uncommon. Again, from what I can remember.
Also keep in mind that billed != settled. If I recall correct, that bill was settled at something around $55K. That was many years ago.