I'd add unit weight in ounces, myself; that's what I use in my Open Office Calc spreadsheet. I have one column for ounces at the beginning of the year, one column for ounces at the end of the year, one column for total ounces purchased, and one column for the amount used. I use ounces because I rarely buy more than a pound at a time, so my remainder is most often less than a quarter pound.
So it might look like this:
GLASS PRICE/lb JAN10 BOUGHT JAN11 USED2010 VALUE
EDP 256 55.00 5.0 12.3 11.4 5.9 39.18
My formulae calculate everything. All I have to do is to remember to update the amount bought when I buy it, and then weigh the glass at the beginning of the year. If I bought a quarter pound of EDP in January and another quarter pound in July, I would have 8.0 as my total ounces for the year.
You could do it in pounds, too; my little scale uses ounces, that's all, and it was easier writing the formulae that always doing conversions in my head
(Yeah, I should just write the formulae to convert for me!)
The new page looks great, by the way, Deb. Thank you for all your hard work!