I use mason jars in canning and have taken food safety courses. (Because yeah, I'm detailed like that.)
According to those, running the jars through the dishwasher sterilizes them. Or you can put the jars on a cookie sheet and in your oven on something like 210 degrees F, maybe? for about 10 minutes. (Double-check the oven temp and time, though. I'm hopped up on a steroid shot and bouncing around like a hamster in a wheel so my fact recall may not be exact.) Either one of those processes will result in sterilized mason jars.
If you can, don't toss the box the jars come in. Just carefully cut the plastic around the side, and you can store empty jars in there with no dust accumulation.
And since I'm sharing the uber-exciting stuff I learned in that class, I also learned that we are supposed to store our mason jars top down so that dust particles can't float into the jars like they would if the open mouth was raised. exciting, huh? lol