Tree Guards

Cheapest tree guards in the States: 74 cents - http://www.gardenersedge.com/subcat.cgi?

Cheapest tree guards in the UK: 31 cents - http://www.thegardensuperstore.co.uk/acatalog/Spiral_Tree_Guards.html

Any other ideas for free/low-cost tree guards? How about vinyl siding from the waste stream?