I homeschool 7 kids... I sent a letter to the County School board office and Just let them know I was homeschooling my kids. I sent their names and ages and grade level. They sent me an information packet, and we do our own cirriculum. the only thing we pay for is school supplies, books, (which we get our text books from ebay) and anything extra-- crafts, snacks, etc. It's a lot cheaper than a years worth of school clothes, lunches, shoes, supplies, and field trips. And my kids are now above level on reading and Math, and my 3 year old can read!!!!!!!!!

Christian Light Education (CLE)
Rod & Staff
School of Tomorrow (ACE) PACE's
LifePacs from AlphaOmega
McRuffy

I use some things that cost a bit more and mix them with things that cost less.  I also try to get things on sale and/or materials i can reuse for multiple kids.  I am currently teaching 2 kids on less than what private school tuition alone cost us for 1 kid (about $1,400/year).