Like most people, I am always happy when I feel that I am getting my money's worth. Don't get me wrong, I can spend frivolously with the best of them, but most of the time, I am able to use common sense.
I have no trouble adding, subtracting, multiplying, or dividing, but other math (what in the h*** is the quadratic equation for anyway?), and anything requiring a lot of theory, goes waaaay over my head. I have just never been inclined towards math.
Except sometimes when I want to determine how much something actually has cost me. For example, I have rosacea, and my dermatologist told me that I should wash my face with something that can be tissued off, so I don't aggravate the condition. She recommended Cetaphil. So every time I start a new one, I write the date on the bottom of the bottle with a magic marker. Then when it's gone, I calculate how much (roughly) it actually cost me, per use. I can tell you that compared to other drugstore brands and a few of the department store brands, Cetaphil is a good deal (and the CVS version of it is even a better deal! But don't get the Rite Aid brand, as there's no pump and it's too watery. But I digress.) There actually have been times when, using this "formula," I have found that more expensive brands are cheaper in the end than drugstore brands. Because I am so pleased when I find a good result, I have been applying it to a lot of other things. (I even determine how much my gym membership is per use over the course of the year. Clearly I need a life.)
I have, of course, shared this wonderful calculating system with others, and though they may mock me at first, a lot of them start using it too. My friend Lisa has even given it an official name: Bridget's Mathematical Spending Theorem, or the BMST. We often compare notes on how something or other stacks up, once it has been subjected to the BMST. (As you can tell, Lisa appreciates the true beauty of the BMST.)
It doesn't work for everything, though. Knitting, for instance, is not really conducive to the BMST, so I have to find other ways to decide if something is worth my money. To use a knitting book as an example, say it contains 20 patterns, and I only see 6 that I could ever even imagine knitting. I don't buy it, because my informal, personal rule is that I must really like - meaning, someday in the universe I may knit - at least half of the patterns. Once that has been decided, it must be a price that I think is realistic and reasonable, at least for my bank account. These requirements, if you will, apply whether it's hardcover or paperback. Has it worked for me? Most of the time. There have been one or two occasions when I later decided maybe I would go ahead and buy the book, and it's out of print, and used copies are going for hundreds of dollars. Then I try to distract myself with something shiny, and/or cake, to help me feel better ...
Yarn is a little bit more difficult. There are so many yarns that I like, and would love to try. But I'm a slow knitter, and I already have a lot of yarn that has never even been next in the queue for a project. I try to go through my stash every six months or so. If there is something that I realize is just never going to be used, or I am puzzled as to why I bought it in the first place, then it gets put aside, to be sold on the Knitswap list, or given away to a good home. But it's hard for me to have any consistent "system" for deciding what yarn I'll buy.
Then there are needles. I give myself a little bit of leeway here, because I have preferences for different needles for different projects. When I knit socks, I like short needles. Something that is going to end up being heavy to hold will go on a circular needle. Straight needles such as you can use to knit a simple scarf, drive me nuts if they are too long. And then there's material: metal, plastic, bamboo, etc. Maybe it's because they can be specific to a type of project, but I am more willing to splurge on a nice set of needles. Once again, though, they are not BMST-worthy.
By now you have probably decided that this is all very weird, and who cares anyway? I think I'm probably the only one who really cares, but thinking about this made me wonder what kind of decisions other people make about their knitting projects and materials, and why. I mean, all financial things being equal (yes, I know they are not, but suspend your disbelief for a second, would you?), what makes some people barely blink when they buy 10 balls of yarn that is $15 a ball, and some ebony needles for $27, while someone else agonizes for an hour over whether to buy the $5 pattern or the $4.99 knitting magazine, and leaves the store to think about it some more? If I were a sociologist, or a sociology grad student, this would probably be a good starting point for a thesis topic. (Note to sociology Ph.D. candidates: please contact me for the correct spelling of my name for the acknowledgements section of your dissertation.)
Of course, in a Bridget-centric world, we really wouldn't need to use the BMST very often, because things would be priced reasonably all the time. But, alas, I'm not the one in charge of the rest of the world, so you're all on your own.