proximity sensors

hey, i need cheap proximity sensors to be used for a range of 2 cm to around 50cm. Plz suggest some good models available. Plz help and reply asap. thanx in advance.

Proximity sensors are not cheap.

Proximity sensors are not cheap.

Haha well said!

What are you wanting to measure the proximity of?

Conducting surface? Metal? People? Liquid surface? Magnetic Field?