Boat service run by Budapest public transport company during summer months might be a good alternative to costly tourist boats.
Though you do not have a guide on board talking about Budapest, you can still enjoy the city views and the flow of the Danube.
The boat runs from Boráros tér on the Pest side and on its way to Pünkösdfürdő it has a few stops including by Chain Bridge and Margit Island.
Ticket for the whole route taking about two and half hours is 900 forints (3 Euros) for adults and half that price for kids, but many prefer to get out halfway on Margit Island which is downtown and cheaper.
The boat is running till August 31. Check the timetables and map on BKV site
