No offense, but if you live in Singapore, you order everything from overseas.
I found Rachmaninoff's transcription in crappy sheet music (one of those random companies that only prints such musical "gems" as Fur Elise, Liebestraume No.3, Minute Waltz, etc...ugh) for $1.50 US. It can't be that much to import it.
I'm a strong advocate for buying music; no links or PDFs here.