Depending on date, less than $200 a night is Hilton Garden Inn in Little India. It's off the usual tourist path, but it's close to an MRT and from there you can get anywhere in Singapore (mostly). Maybe a 20 minute walk to a bunch of malls but there are good restaurants on the side streets. I'm not a fan of Orchard Road but it's easy to get there on the MRT from Little India. Little India is a terrific place to walk around and there are some good Indian restaurants (the best is Mustard).

I think it would work if you're adventurous, if not then it might be a stretch but anything on Orchard Road or near the convention center is going to be really pricey.