I've only just started in this game but I think I can claim to be pretty green......
Petrol in my home town in New Zealand is around $2.20 a litre (4 litres in a gallon). If I happen to be in an area where there is a cache, then I'll have a look....... I can't really afford to drive around the countryside looking for tupperware.
Okay, maybe Harry Dolphin is right...... I'm just cheap, not green