Here's my smoothie recipe--for what it's worth.
4 oz. plain yogurt
3-4 oz. tofu
4 oz. soy milk (or regular milk, but I try to get as much soy protein as I can).
I blend the first 3 ingredients until smooth then add:
2 Tablespoons Splenda (or to taste--it depends on the fruit you use). You could also use honey if you wanted.
1/2 - 3/4 Cup frozen mixed berries (or whatever fruit you like)
blend to desired consistency and then add:
1-2 T wheat germ
1-2 T ground flax seed (I buy the whole flax seeds, which are inexpensive, and then grind them in my Braun mincer-chopper).
You can experiment and find a variation you like. In the summer, I leave out the soy milk and add more frozen berries to make a pseudo-ice cream. It isn't Haagen-Daaz, but it keeps the cravings at bay.
This is a staple for me. My kids love it, too (without the wheat germ and flax). My 10 year-old son loves peach, my 8-year-old daughter prefers strawberry but will settle for mixed berry, and my 5-year-old son loves berry-banana. And they even like the tofu. I just mix a big base-batch and then mix their respective fruits.
This is easy, inexpensive, and very nutritious.
I buy Splenda, frozen berries and soy milk at the warehouse stores like Sam's and Costco. I also purchased a Salton yogurt maker, because I use about a quart of yogurt every day or two.
Hope this helps,
Carol F