Beppu station to Hells in Kannawa

I'm aware the Kamenoi bus pass cost 900 yen.

The link below also states the Kamei bus number 5,7 and 9 can reach Kannawa in about 15 minutes from Beppu station.
http://www.japan-guide.com/e/e4702.html

Would someone be able to tell me how much is a single bus ride from Beppu station to Kannawa on the Kamei bus?

I think 320 yen for about 15 minutes ride.

The above info sounds right. Actually 3 of the Hells are literally next door to each other, and 3 more are just a few minutes walk beyond that. Only the last 2 are a bit of a pain to get to - the Tatsumaki and the Chinoike hells. The Tatsumaki is a geyser that goes up every 25-30 minutes or so. The key to maximize your time is to go there first, then if you just missed the last eruption go see the Chinoike first.
If you want to see a good video of all the Hells, see:
https://www.youtube.com/watch?v=K2NNi8MLcXM
You can get through all of them in a few hours though, so if you want more to see, try the Takasakiyama monkey park & aquarium. You
walk walk among the monkeys and watch the stampede when the food comes out. See:
https://www.youtube.com/watch?v=zepPfkuqhok
Mt. Tsurumi also has a great view of the city and bay if the weather is good. See:
http://www.youtube.com/watch?v=cBnZneDsKqQ
Beppu City also has a lot of info on
http://www.city.beppu.oita.jp/02kankou/english/01info/02shisetsu/index...