I've found the interest rate on outstanding debt to be a tremendous motivation to try and limit the number of frivolous things I buy. For example, our interest

I've found the interest rate on outstanding debt to be a tremendous motivation to try and limit the number of frivolous things I buy. For example, our interest rate is 5.5% and we're not due to pay off our mortgage for 28 years. That means (more or less) that for every dollar I spend, I could have put that on my mortgage and saved 5.5% interest (compounded) over 28 years. Another way of looking at it is that I'm going to be paying 5.5% interest (tax-deductible) on anything I buy instead of putting the money in an extra payment on my mortgage. Given the terms of my mortgage, that makes an $500 iPad actually cost about $500 now and another $481.06 in interest over the next 28 years. My $2300 MacBook Pro will actually end up costing me $4512.88. The great thing about this approach is that it doesn't discourage me from buying nice things that are actually worth their value. The MacBook Pro for example produces incredible value, much more than I paid for it. However, knowing that for every $5 smoothie I buy now, I'll be paying another $4.81 for it in 28 years? I don't buy $5 smoothies 2-3 times a week anymore. Instead I go to Rita's when they're doing $1 kids cones on Monday and I go again on Wednesday for the $1 Italian Ice. Anyways, I found this so helpful in curbing frivolous spending that I created a small iPhone app to help folks do the calculation on the fly. http://whatll-it-cost.limelightapp.com/ http://whatll-it-cost.limelightapp.com/ . I'd be happy to give a promo code to anyone who thinks it'll be helpful. (After all, that $0.99 would actually be $1.94 after 28 years at 5.5%. :p)