I'm a subscriber to the 'Nikon Owner' magazine & as it's a Grays of Westminster publication it gives you many other benefits including extended warranties on all their second hand equipment, technical helpline & going on the priority list for new gear.
I used to subscribe to Nikon owner too, but not anymore. I know you can buy over the phone but it is more of a faff when a PX is involved especially when it is vital that the Wife does not and must not know. She knew that I got a D70s in early 2006, but since then I've had a D700, D810 and a D850............
The D810 and D850 were bought when Nikon were doing the enhanced trade in. Got £445 for my D70s in 2015 and £300 for my D300. The enhanced PX was not so good for the D300 in 2018 but I'd already got a Fuji XT-1 to replace it and I wanted the D850.
It was a lot easier to do it in store without having to go to London.