If you are into cycling then the latest garmin edge 1030 plus, which I think normally retail for north of £515 is available to Blue Light Card holders for a great (but still steep) price.
It not a spontaneous purchase, but a phenomenal bit of kit. The bundle (with HRM etc) is £449 (usually 600 plus).
This has all usual metrics and new navigation features.
There is a comprehensive review on Garmin Edge 1030 Plus In-Depth Review | DC Rainmaker
to understand what it does.
Many cheaper cycle GPS, and some use a phone. Nothing combines features with battery life like this.
I have just moved from and Edge 820 to this, and totally love it. The big and responsive screen is great for my aging eyesight.
To get the right price, you need to log into the Blue Light Card website first and follow links to Garmin website.