AF due today, is it worth testing or waiting?

I'm trying my best to be patient but it's so hard! AF is due today however it's not unusual for me to be a a day or two late. I never suffer from cramps until I am actually menstruating and I rarely get tender breasts so it's hard to tell if she will arrive or not!! Problem is, pregnancy tests r so expensive I'm reluctant to buy one just to find out that AF is just late. Anyone have the same problems and have any suggestions?