The size you're looking for is 2R, cost is usually $1 to $1.50 at most photo lab. The other alternative you can ask for is 4-up, which is 4 photos (usually the same picture) in a 4R photo size. Its abit smaller than 2R. Not every photo lab might have this so u have to ask around. KT at Hong Lim Complex does this.
Serious mahz ? haha.. i locatEd in West Side of Singapore, haha... where u living in ? Oh, BTW, anyone knows how to make photos like NEoprints ? clear off the background with ease, then put a few nice nice fake stars and heart on the pictures ?