I think it was 32 Euro per adult and 15/16 Euro per child when we went in April - but I could very well be wrong, knowing how rubbish my memory is! lol.
Anyway, we always have a meal there too (well, I say 'always' but we've only been to DLP twice and we've had dinner at Cafe Mickey both times). We booked dinner for 6.15 pm and it was good timing really. Not too busy to start off with, so the characters tend to spend a bit more time with you at the beginning. We were out of there two hours later.
I would say definitely make a booking before you go. I'd rather not be disappointed when I get there and not be able to get in. Even if you change your mind when you're there, you can always just let them know.