You are probably figuring that you will only use it once and then never again, so why not save a few bucks, right? I think you will find that it comes in very handy and you will get more use out of it than you may think.
Everytime you change components or settings, you could be in need of the meter to recalibrate. Add or remove furnishings and you should recalibrate. Curious what the SPL level is when watching your favorite movie or listening to music, you need the meter.
It's a good tool to have and they are relatively cheap, so just go get a shiny new one at your local Radio Shack. You'll be glad you did.