All depends on where I am & what time I need to be away in the morning. If I know in advance I'd be over nighting I'd budget for digs in that area & book ahead where possible. But I have no problem sleeping in van when necessary & always keep a 4 season sleeping bag & overnight night bag in van just in case.
I slept in an Escort van in a Belgium service station about 15 years ago coming back from Luxemburg & it was that cold, when I woke up my head/hair was frozen solid to the window. Sleeping in the van wasn't much fun that night.
As for how much I'd pay for a room that would depend on the price given for the job & what's available in that area etc. When I was in my 20's & 30's I'd happily sleep in a van but these days I don't mind paying for a bit of comfort.