I got a Sylvania-branded strand of 50 "warm-white" LEDs (plus two loose spares) for USD 2.50 at the local grocery store, which I'm pretty sure is cheaper than buying a bag of the bare LEDs would run. They also come in other colours (blue, cool-white, bright red, multicolour)

The individual LEDs come in plastic shells which can be cracked open to retrieve the goodies inside, and have plenty long leads that are folded over to fit the "bulb" mounting.