Stayed at Gundabooka NP near Bourke a couple of days ago. They seem to have a combination of online bookings and pay on site envelopes (don't ask me how that works, but the envelope system DOES work). Well despite the box for the completed envelopes being bloody huge, it was almost impossible to stuff mine in as it was overfull! I rang NPNSW to suggest they go and unload it. Good to see people paying, bad that they can't be bothered collecting the money - are they trying to make the system fail? Anyway, if you haven't been, this is a great spot with rock art, utter silence, good facilities, but take your own wood and water.