1/ Decathlon sell their own brand for cheaper than the branded ones and I’m pretty sure they’re actually KMC ones.
2/ Get a pair of powerlink pliers, well worth a fiver and space in your pack. You can thank me first time you need to split a chain in the cold and wet with numb fingers. http://www.chainreactioncycles.com/x-tools-pro-master-link-pliers/rp-prod55925
3/ Get a spare and tape it onto your bike somewhere so it’ll always be there (old school – in a bank coin bag shoved up inside your seat post)
4/ Carry a spare spare too – and if you make this a 9spd one then you can use it on most chains you come across – it’ll also fit 10 or 11 at a push, won’t run as smooth due to a marginal increase in width but it’ll get you home / back to the car. I’ve saved someone’s ride a few times with a spare 9 speed link.
(reminds me – I don’t think I’ve replaced it since the last one I gave away)