Best use of budget

I moved on 5 years ago and if other members like/don't like the science that is up to them. As for a budget, I don't have one, I am in the fortunate position of being able to buy what I want when I want it.

Roger

You are missing the point. It's not what you can afford or even are able to finance. It's a question of what would you prioritise at the various price points, the idea being to build a picture of which modifications are popular and or deemed relevant or even necessary, such that someone new to the arena of jimny might be able to make an informed decision on where to place their budget. It's also an opportunity to see where some of our regular users might just be heading with their build evolutions.

Sub £10: replace 12V socket with a multiport USB charger socket
Sub £50: replace front speakers
Sub £100: install rear speakers or fog lights or box in the back
Sub £500: street legal front LED light bulbs and LED fog lights
Sub £1000: roof rack, if the car is not old: Mike Sanders corrosion protection fat for the complete underbody (maybe this was my very best investment to keep the Jimny in a good condition)

The price points are difficult, as everything is so expensive nowadays, the bubble of 1970s that I live in has had a rude awakening!

For the Gen 4

Sub £10 a pair of heated rear window wire protectors/covers

Sub £50 Kayak D rings & screws to fill up all the M6 holes in the back, a cargo net and a few large aloominums carabiners (to go through said D rings and the handles of shopping bags to stop them spilling out on the way home), a decent electric tyre pump.

Sub £100 Difficult, not much that I'd consider useful here, everything is below £50 or above £100.
Maybe half a dozen cans of Bilt Hamber Cavity protection wax

Sub £1000 (Would have been  my sub £100 but I can't source one under £100) Transfer case skid plate.  
Otherwise tyres.