Money money money

Homeschooling seems that it will cost a fortune.   I am not even buying a curriculum (a la Abeka or others) but I still can't stop spending money.  I have chosen homeschooling because I want what is best for my daughters and that is translating into new books and possibly one each of everything from Carolina Supply.  We are going to do some plant studies and I am ver interested in the Wisconsin Fast Plants. However, unless we are going to do genetic crosses do we really need fast plants?  Is part of homeschooling the ability to do experiments over a longer time period?  Could we learn as much propagating something cheaper?  Where else should I cut costs?  I already plan on being a fixture at our local library and not buying books that I can check out.  We have a learning co-op in the area that we have signed up for.  Hopefully I can learn more during our summer activities together.  I hope the other parents can help me cut some costs.