There are some great deals with Amazon Prime Day 2018 so far this year, in particular, the fitness category has some amazing deals.
Some of these are lightning deals and are currently live, so you will need to be quick if you are interested.
This is £50 cheaper than it has ever been and it would make it £250 cheaper than the newly announced Garmin Fenix 5 Plus so if you don't need music or NGC payments then this is a scorcher of a deal. The price appears to be for select colours, the normal Fenix 5 in with a Granite Blue Band is £349.99 or the 5S with a Turquoise band is also the same price
The Forerunner 235 is the watch I currently use, it has some quirks but for the price, it is about the best option out there. I think this is the cheapest it has ever been, with normal sales being around £170.
If you want something a little more stylish than the Forerunner 235 the Vivoactive 3 looks like a great choice, it costs a little more but it uses the latest software by Garmin and includes things like NFC contactless payments. Though this is not the music model.
If you want reliable heart rate monitoring then you need to sack off the wrist-based HRM on all sports watches, they are gone to some extent, but prone to spikes and drops. The POLAR OH1 Heart Rate Sensor is still optical but its placement on the upper arm gives a reliable connection and I have found it to be superb, much more convenient than a chest-based strap.
If you don't fancy using Garmin the Suunto Spartan is currently about £20 cheaper than it has ever been.
If you just want general step counting and heart rate then you can't beat the Fitbit Charge 2, its social features make it stand out from the crowd and at £79.99 it is a bargain
Also, don't forget if you are an Amazon Prime Student member you can get £15 off a £60 spend with the code STUDENT15