For digital pics, I develop them in Far East Plaza, Orchard for S$0.25 for each 4R sized photo.
For film, I used to drop them off at those Kodak boxes at the check-out areas in Cold Storage and other locations. It costs $9.95 to develop the whole roll into 4R sized photos (all inclusive price). It doesn't matter if it is a 12, 24 or 36-exposure roll.
However, I must say that my digital camera is worth the investment as I now print only the best ones and share the rest on-line with friends and family.