pressure sensor advice

hi i wanted to ask in anyone has ha much experiece with using pressure sensors and arduino. I am currently designing an interactive walk through tunnel space, through which the audience will be allowed to go one at a time. I want to use arduino in combination with some pressure sensors located on the floor of the space to trigger a selection of sounds and lights. I am interested to know what results people have had with regards to designing pressure sensors? At the very basic it could just be two wires that when connected trigger an event. I have been suggested to look at using cardboard to help spread the pressure evenly so that the user could step anywhere on to the sensor and trigger the necessary event. I have also been looking at infrared and ultrasonic sensors but this seems like a more costly solution especially as i am only looking for on/off triggering capabilites. Any thoughts welcome

Oh, not AIR pressure... you want to sense WEIGHT.

Here is a simple DIY approach:

Using a divider and A/D (analog input) you can make it ON or OFF depending on the value you read on the pin.

thanks for the reply - i am going to give that a go this afternoon. I have also come across some pretty cheap pressure mat's - these are intended for security purposes (slot in under the carpet to detect an intruder) but are priced as low as £2.99 on ebay - ordered one today to see what they are like, but if the sensor is equally responsive along the whole mat, then it could be the perfect solution.