It is entirely possible to make healthy smoothies in a regular blender. You don't need to buy a super-expensive high-powered one, unless you use tough ingredients or use it daily. In my husband's country, people regularly make "smoothies". Two of the most popular ones amongst the immigrants are as follows:
Fill blender with milk and add 1-2 bananas and 1/4 cup sugar. Blend 30 seconds.
Fill blender with water and add 1/2-inch chunks of freshly-cut pineapple and 1/4 cup sugar. Blend 30 seconds.
Naturally, both of these recipes can be tweaked easily. I'm guessing the Pineapple smoothie recipe uses water instead of milk due to the acidity of the fruit. It seems to me that mango would pair quite well with it. As for the banana smoothie, bananas love strawberries! And feel free to experiment with using honey instead of sugar - honey is very healthy.
Now here's a recipe I just tried out tonight. I can't remember which website I found it on, but I tweaked it because my blender is too wimpy for ice:
1 cup chilled water
1 drink-juice box of Orange Juice
1 cup red seedless grapes
I tested the recipe out on my 3-year old who suggested I run it through a strainer because the grape peels added a bit too much texture for her liking. I tried it as well and think it could do with some yogurt, but that might be personal preference. Try it out and tell me what you think!