I have a feeling that they offer these extras at crazy prices because they really dislike doing them. They reckon if the price stops people from asking, all well and good. If however a punter is desperate enough cough up this price, they'll swallow their pride and do it. At those prices it would discourage most punters and steer them towards the standard service.
A bit like the tradie who already has more work on than he can handle, so he quotes any new jobs at 2 or 3 times the going rate. If you're mad enough to pay, he'll find a way of fitting you in. If you tell him to piss off, no skin off his nose because he already has more work than he can handle.