Nelia&Albert

Here's a great thread for hotels in Manila pinned at the top of the main Philippines forum page: http://www.visajourney.com/forums/topic/328357-h0tels-in-manila/
Hard to say which one is the cheapest unless you investigate them all. Although, Grand Prix I think seemed to be one of the cheapest I saw in the Ermtia area. Travel sites such as Agoda or Trip Advisor etc. might be good place to compare and shop around.