Maybe a little time. Go through what you already have. Chances are these materials can be used to help with your homeschooling. Good books can be reread . Toys can be used to explain physics.
Games provide delightful practice in a variety of areas.
Ask relatives and friends for attic treasures such as microscopes and telescopes or costumes for make-believe. Learning materials will trickle in. Fellow homeschoolers who have outgrown materials are another great resource. You might find some real treasures in Goodwill or thrift stores and garage sales. There's a great geometry lesson in building some nice, solidly square, bookcases to hold all this stuff.