Math: Math-U-See : $136 : https://store.demmelearning.com/primer-universal-set.html
(A lot of what your buying can be reused for other children, and can be used for next years math.)
Writing: Learning Without Tears: $19 : https://shopping.lwtears.com/product/SBK/products-by-type
Cursive: Learning Without Tears: $10 : https://shopping.lwtears.com/product/CH/products-by-type
(if you are interested in a good cursive workbook this one is great. It is recommended for Grade 3, but simply exposing your child to the concept is always beneficial. They might not take to it this year but when they do it will come more easily.)