We took the trip to Pl;itvice last week, we booked at an agent by the Marina in Borik and it was 540 Kuna each, we had been quoted 550 a couple of days earlier by a different agent, A minibus picked us up from our apartment and took us to the park with a stop on the way for breakfast, omelette and tea was included in the trip price, anything else, coffee etc was charged extra.
Our guide round the park was very good but I did feel we were rushed around a bit, I would have liked to have stopped a bit more often to just admire the scenery, after the tour it was back onto the minibus with a stop at the same restaurent on the way home for a chicken and chip dinner, again included in the price but drinks extra.
The minibus then dropped us off at our apartment but we were told we could be dropped elsewhere if we preferred.
We were picked up at 08.30 and got back about 6, so I guess that explains why we were a bit rushed around the park.
Given the chance to do it again I think I'd look into hiring a car to allow us more time in the park, possibly even booking a nights accommodation near Plitvice.
Admission to the park was 110 Kuna and we went on a toll road that I think was about 80 Kuna for a car.
Overall I think the price was reasonable given the service and food, there are plenty of agents selling Plitvice trips in Zadar and October will be late in the season for them so you may get a better deal than we did, chat to a few of them and see what's included and how long you get in the park, or hire a car and make your own way, the roads are very quite compared to Britain and the park is well signposted.
Have a nice trip.