Do you know what the difference is between a smoothie maker and a blender? As far as I know, you can make smoothies with a blender, so what is a dedicated smoothie maker for? Is the only difference that that a smoothie maker has a tap to dispense the drink into a glass? Here's a snippet from a Times article that ponders a similar question:
The Smoothie Maker, to be honest, I consider to be the last straw. A Smoothie Maker is just a blender – IT’S JUST A BLENDER! – but with a tap on the bottom. A small, useless tap which will, on the first day of use, become clogged by a single strawberry seed, leaving you flossing the tiny nozzle with a pin until 4am, weeping. A Smoothie Maker basically marks the UNINVENTING of the blender. It is a negation of progress. It’s like having sex with monkeys. It will do humankind no good.
Whilst Googling the answer, I found that someone had asked the exact same question over at Money Saving Expert - so have a look there for some interesting replies too... the funniest one being "about a tenner"!