Testing components for DIY hotplate+stirrer

So I was lookink at some hotplates. They are quite cheap so there is no point in making your own. BUTT, maybe you are familiar with NurdRage's story of failing of multiple hotplates and desire to repair / replace heating elements. And also WTF do you want to achieve with 150W of power - usually the cheapest models. Like to heat 1l of water to its boiling point you will need 45min at full power...