I have been looking as well - there are a few 'short time' hotels in the Malate area off Quirino Avenue - the Soho Hotel and Victoria hotel - for 1,200 pesos a night. These are basically 2 star hotels - single room, bathroom, cable tv, air con, double bed. Nothing flash
But all the three star hotels are around the 1800-2000 pesos mark. There might be a few around the 1,600 pesos mark. I know that the Gran Prix hotel in Pasay - near the bus terminal and 30 minutes drive from the airport cost 1,400 pesos for a normal room.
I was thinking to get an apartelle - which would cost 1,600 pesos a day. But its hard to find anything close to the airport.
Apart from that everything else is around the 4,000 pesos cost per night. Just depends on what your budget is.
there are quite a few sites that you can search that will likely show you great hotels at the best prices available. check out the website BookMe and you will be able to compare prices on all the reputable travel sites in just a couple minutes. it's very convenient and will save you a bunch of time and money. Also, make sure you buy them online... otherwise they charge much higher fees for phone orders. good luck.