My husband and I make smoothies almost every single night (as in, 6-7 nights/week), so we're really hard on our blenders. We have been through 4 blenders in the last 3 years alone. We started with a cheap Oster blender, but quickly realized that it was pretty much useless for the thick smoothies we like to make. Next, I bought the Back to Basics Smoothie Elite, which was great for as long as it held up, but as it turned out, that was only 6 months. So, we upgraded to the Back to Basics Smoothie Professional, which was great until I dropped the glass jar into the sink and broke it, only to find that you couldn't buy a new one ANYWHERE so my $120 blender was now worthless.
After all this, I decided to stop fooling around and buy a Kitchenaid. This blender has all the power you need (way more power than any of the first 3 blenders I bought; both the smoothie blenders came with a stir stick, but such a thing isn't even necessary when you have the power of this Kitchenaid), and is a steal at $99, since we've had it for a year now and it's still as good as new. The motor is unstoppable, the blade is fantastic, it cleans easily, the jar is polycarbonate (i.e. unbreakable if you drop it), and there is a removable plastic piece in the lid in case you do want to use a stir stick.
I love this blender, and when it dies (which I hope/believe will be years from now, given how reliable my other Kitchenaid appliances are) I will be replacing it with the exact same make and model. It's everything a blender should be!