We buy year-long memberships to our favorite places, but there are always a few that we really only want to try once or twice. This is where Groupon is really useful.
You do not need to necessarily participate in everything offered by local homeschool groups, but at the end of school year, many of them sell items that they no longer need.
If your student is struggling in a certain area, or there is an item that you tend to need a lot of, most dollar stores will have inexpensive workbooks and school supplies you can purchase in bulk.
Many homeschool programs are free or significantly discounted. We use Pinterest searches to help us find different activities, programs, and curriculums that are offered for free.
Since you are homeschooling instead of sending your children to public schools, you have the luxury of waiting a few weeks after the school year to replenish your school supplies.