November 4.-December 31.ig 08-18ig.

I asked exactly the same thing. We were told that you had to pay an entrance when the museum was open, but the castle grounds are free to walk around when the museum is closed. So most of the time, you have to pay, even if you don't want to go in the museums (though they were more interesting than I expected). There was a note explaining this in Hungarian (which I could just about work this out from), but the girl on the ticket booth explained it to my Hungarian companion too, so it is definitely correct.

2.000 HUF entry