Prime is an extremely smart program. You WILL end up spending more money at Amazon, but it's OK because their prices are great and you end up saving an incredible amount of time. You have to be careful to use it efficiently (and not "shop"/browse and accumulate too much stuff), though. I've bought thousands of dollars worth of stuff over the past few years--electronics, books, toothpaste, vitamins, and even oatmeal--and haven't been to Bed Bath and Beyond / Walmart / etc. in ages.

This means I can do enjoyable things on the weekend instead of running errands.