DS's reception class can go on an overnight stay at a camp type thing (they sleep in actual dormitories, it's a bit like an army barracks) I remember when I went in the 1980s and it cost my mum about tuppence ha'penny. Got the letter yesterday and it's sixty quid! 
That includes transport (mini bus 10 miles up the road), dinner and breakfast and the "activities" and the overnight stay.
I think that that is effing loads for a reception overnighter. AIBU? There will be parents who can't afford that. :(