Try Reliance Travel in Singapore
http://www.reliance.com.sg
And click on S'pore hotels there...
Some good quality hotels there for around S$100. The Hilton on Orchard Road goes for S$185/night. I would use BiddingForTravel.com though and bid through Priceline (sometimes the regional pricelines may be better - ie priceline.com.sg or priceline.com.hk)
Marriott is definitely worth getting if u can get it through priceline, excellent location cnr scotts and orchard and next to the orchard MRT.
enjoy SIN!