This isn't a necessary item for canning, but it can be a good investment. If you are going to make your own jams/jellies, then this will easily help you separate seeds and skins. It can also be used to strain jellies if needed.
Remember, when you are starting out from home on a budget, all the above items will not cost you more than $300, but when you start to grow big, you may want to start investing in more commercial grade equipment. I will touch more on that later.