The £20 per month for 2 months Sports Membership is also available on the NOW website by going to this link below and not going to the NOW dedicated offers page section on their website where it only shows the £25 per month for 3 months deal, if anybody hasn't got these two offers under their my Memberships "Exclusive Offers for You".
I would have taken up the 2 months for £20 per month offer, but my current sports deal has more than 30 days remaining where i could have saved myself £5 per month for the two months left on my current sports offer.
While @Saint1976 is correct if you want or need a Stick, you may already have a suitable device or devices, perhaps even your TV.
Have a look at this list of supported devices:-
Of course, you may have one or two devices on the list but that would be inconvenient to use for this. In which case, it’s back to the Roku/Amazon choice.
But if you have a device on the list that you want to use, but you can’t see the Now app on it, try downloading it from the content store offered by the device.
Republic of Ireland NOW customers can still buy the NOW Smart Stick from the NOW ROI website (don't know how long NOW ie will keep selling it on their ROI website).
Where the ROI NOW Stick version can only be used in the ROI with a NOW ROI account.
Agree with everybody else who has already mentioned it, if you haven't got a suitable supported playback NOW device, then look at the Amazon Fire Stick or Roku Player.