There are many good workbooks available for kindergarten children. However with a regular workbook, a child can do each activity or worksheet only once. A good option is to use printable kindergarten worksheets. These are basically digital versions (like ebooks) of worksheets that can be bought and downloaded to your computer from the internet or from CDs and then printed out. The advantage is that you can print out whichever sheet you wish. If you need to re-inforce a certain concept more you can usually print out that sheet again. Of course you will therefore need to have a computer and a printer.
To Pay or Not to Pay? There are hundreds if not thousands of free printable worksheets available online. These are ideal for filling time or keeping the kids busy on a rainy day, but few of them offer a systematic set of worksheets with activities designed to teach your children a specific set of skills. If education is your aim, you may have to spend a little to get useful, comprehensive worksheets that actually help your child to learn.