OK I will tell you of a place. Go to Marine Parade town centre (the open square opposite Parkway Parade). Basically, opposite the DBS Bank and UOB Bank. You will see a square next to the hawker centre/food market and some ad-hoc pushcart shops lined up on the square.
The second shop (on the left hand side) is a key duplication shop. I cannot remember the exact name but their slogan is "THE MASTER OF ALL KEYS".
Here, you can get all kinds of keys done. Including condo access cards and so on. I remember asking them about re-programming/duplication of car remote keys and he told me a price but I cannot remember it exactly.. should be between $50 and $100.
Don't say I'm trying to promote any commercial services hor. I only revealed the location cos you asked!