I homeschool my children but also live on a budget so affording text books is kind of hard.  I found a great solution though, the school express website offers thousands of free printable and downloadable worksheets and workbooks. 

The workbooks are my favorite. Take History for example: There is one workbook with the actual worksheets on the specific subject and then a matching workbook with activity worksheets (puzzles etc.).  It's really great, free, and my kids seem to enjoy them.

These worksheets and workbooks also make organizing my lessons for the week a LOT easier.  I hope you find them as useful as I do. http://schoolexpress.com