I'm guessing this is a price glitch but if you go onto the Argos Tlink page at the bottom is a special offer for an Amazon Echo plus two Tlink Smart plugs for £74.96. However every time i build the offer it comes to £94.96. But if you go into store they will honour it saving over £35 when bought separately!!
T-link Smart plugs need no gateway to work with the IOS or Andriod app. Also works with Alexa and Google Home.