It's £3.50 each for a day ticket. Don't ask for a single, it appears to be £1 more... that's Aberdeen in a nutshell, really.
I'm glad you're going- Aberdeen has been resting on its oily laurels for decades and only now, far far too late does there seem to be any momentum behind the "you know, people might want to come for a visit" idea.
It's not a bad place really but like others have said the most touristy stuff probably involves a day's hire car to get out and about a bit- public transport is not really much good for where you'd want to go. Perhaps do one day in the city and one in the country. There are plenty of blogs and articles with all the hidden gems of the area scattered around the internet given we are trying to appeal to visitors now.
Signed
A hypocrite who left the city to it's fate and moved to Glasgow
