I have owned loads of blenders in the past, and although cheaper blenders will do the job you have to be more careful to add more liquid, add food in certain orders and blend for longer. And still the smoothies are often a little bit rough in texture.
Some of these blenders aren’t the cheapest, but they are the best. You definitely get what you pay for with blenders and although high speed blenders are much more expensive than some of the cheaper options in this list, you will definitely notice the difference in the quality of your smoothie.
Of course you can use high powered blenders for much more than just smoothie making such as making peanut butter and coconut butter which you would never be able to do with a cheap blender.Ninja Master Prep (QB900B) Hamilton Beach Power Elite Multi-Function Blender with Glass Jar (58148A) Ninja Professional Blender 1000 (BL610) Magic Bullet NutriBullet 12-Piece High-Speed Blender/Mixer System Oster Pro 1200 Blender 2-in-1 with Food Processor Attachment and XL Personal Blending Cup