Why hadn't anyone thought of this great way to shop?
An amazing new app as you have never seen before, Interest in Shopping can save you hundreds, even thousands each year on the things that you shop for. Try it right away with newspaper ads and see how good each sale is, especially for you, at your consumption rate, your money rate. Better yet, try it at the grocery store and you'll see how much fun it is.
Say you find a sale or volume discount and so are considering buying more than you usually do. It could be a sale on bananas, or a season's pass, a lawn cutting contract or anything else. Simply enter a little information and it will calculate your Saving Rate based on your consumption rate of the product and (if you wish) your cost of money. That Saving Rate is just like an interest rate -- the higher the better --, indicating just how good the deal is for you and only you.
It computes that by applying your cash outlay against the present value of all money you'll save down the road by not having to go buy more (because you'll have bought more now). To do so it determines when each of those foregone purchases would have been occurring, and then present-values the money you would have otherwise spent at each of those points in time. Works is any currency: dollars, yen, whatever.
And the best part is that it makes each deal you consider comparable to every other deal you find: apples to oranges or laundry service to flight time, those with the higher interest rates are the better deals for you!