dont necessarily need a wide band sensor, will be far more accurate with 1, but if its just a basic air/fuel gauge being fitted, then a basic lambda will do. most newer cars will only run the narrowband type as standard anyways

i think VAG bosch lambda's are the 1s to go for, pick them up on ebay for about 40quid new, but if u just want a reall boggo sensor, they like a tenner on ebay, plenty of them