I've been making my own smoothies the past couple of weeks. I am using...
1 frozen banana (20¢)
1/2 c frozen berries (60¢)
2 cups of spinach (40¢)
1 T flaxmeal (5¢)
1T peanut butter (20¢)
3/4 c almond milk (25¢)
So if my calculations are correct and they probably aren't but I'm assuming I'm in the ballpark, $1.70 for one.
Except... it makes three times the amount I usually drink. So I've been feeding it to the kids. Nels is a big smoothie enthusiast. I let him pick out whatever he wanted at the grocery store this week and he picked more almond milk. I asked him what he wanted with that and he said he wants to make more smoothies. Okie dokie.
Homemade smoothies I calculated out at 56¢ for an 8 oz cup, store brought at 96¢. I think homemade could be a little more wasteful since some mornings it doesn't all get drank. But since it takes some work I'm more likely to skip it. With store bought it probably gets drank faster since it's so easy but once it's gone, it's gone since I only buy one a week. With homemade there are lots of substitutions available.
I'll be sticking with homemade for awhile but I bet I find my back to store bought.