I haven't had to purchase bulbs for our night lights for years. To make this happen, I saved all the holiday bulbs from our old strings of lights when I switched to mini's. The old colored bulbs fit right into the night light bulb sockets and the light is slightly dimmer so it is just enough to enable you to get around in the dark and not so bright it keeps you from falling asleep.
Maybe right after Christmas when they have the sales might be a great time to stock up (or) look for them at garage sales. I can not believe how much these are any more, even at the dollar stores.