I like to just put in what the regular price of items are and if they’re on sale then it’s a bonus. That way I have allotted enough money for shopping trips and budget the right amount of money without expecting the sale price. So whatever I can get on sale is great cause I’ll have extra money (end goal). Plus, if you’re short on money for a week, you can figure out what meals cost you the least to make and go buy those.
I hope this helps motivate you to do your own! There are some formulas involved that I’m not so sure about because my BIL did the spreadsheet but you can do a simpler one without check boxes and just total up everything if you’d like. Happy budgeting and planning!