There is no need to buy long underwear in the winter when you have purchased the tight fitting pajamas for your kids. These can double as longies.
A few turtleneck shirts purchased on the spring clearance rack for your kids can eliminate the need for long sleeve t-shirts and sweatshirts. My kids wear their summer t-shirts all year round. In the winter, we put a turtleneck underneath them and that is the same as wearing an undershirt under a long sleeve shirt- its just the opposite is all. Turtlenecks on clearance at our local superstores can run under $2 here. One for every day would run you $14 versus buying long sleeve t-shirts that will run you around $8/each (for a weeks worth , $56). This is not counting the white undershirts that you’ll buy to go under the long sleeves too.
Buy full zipper sweatshirts on clearance in the next years size and these can be used for a spring/fall jacket, a sweater in the winter, and an extra layer under their coat when playing outside in the snow.
If you have all boys or all girls or at least 2 of a kind, hand those clothes down to the next kid. I buy school clothes that then become play clothes the next year for the next kid. If you take good care of their clothes they will last a long time. There is absolutely nothing wrong with wearing a stained t-shirt out in the back yard or fishing with dad. Save the good clothes for school, church, etc. and they can be passed on to each of your kids and then given away to neighbor too!!
Don’t be afraid to buy your kids coat too big. It will last more than one season that way and you will have saved immensely. I wouldn’t buy shoes too big though, this can damage your child’s feet.