Lars, I am not sure if this is still up-to-date information, so take it with a grain of Thai salt.
Regular ferries from Bali Hai Pier costs 20 baht and take 30-45 minutes - departure times: from Pattaya 07:00, 10:00, 12:00, 14:00, 15:30, 17:00, 18:30; from Ko Laan 06:30, 07:30, 09:30, 12:00, 14:00, 17:00, 18:00.
You might want to investigate Ko Phai for somewhere a bit nicer. It is ~23 kilometres offshore, so I am not sure what that translates into in terms of travelling time? Maybe 90 minutes or more?
http://www.thailandguidebook.com/pro.../m_pattaya.jpg