The Illustrated Encyclopedia of Metal Lunch Boxes by Allen Woodall, Sean Brickell (1999, Paperback, Revised)

This is a very comprehensive guide to metal lunchboxes that is a great resource for collectors. The photos are fantastic and the guide also discusses the rarity and grading of items. There is a section about pricing, but lunchbox pricing is pretty subjective so I wouldn't even say the prices are "ballpark" figures. The prices listed are more useful to help you figure out what boxes are more valuable than others. I particularly liked the section about care and cleaning which provided ideas I would not have otherwise considered.