ok. Assume you rigidly stick to the legal byways on the plains and don't venture were you shouldn't? Personally don't recall the terrain being all that challenging in that area.
As for vehicles.
D1's will be in scope most likely. But prices are on the rise. The D1 is a good solid 4x4 and is pretty much identical to a classic Range Rover underneath. Which means it is also essentially the same a Defender, just a different wheelbase.
D1's are generally pretty simple vehicles and easy to work on. The chassis is normally good, but the body can suffer some rust, although usually quite repairable. You have a choice of 200 & 300 Tdi engines, which are both very similar and as good as each other. And the Rover V8. 3.5 for early models and 3.9 for latter ones. The V8's are faster, smoother and more refined. But expect 12-18mpg. The diesels are good engines and easy to tune at home. But less refined and make more noise. Expect 22-28mpg. Most diesels are manuals and most V8's are autos.
Off road the Disco runs smaller tyres and has longer overhangs front & rear compared to a Defender. And a bigger, wider body. Apart from that they are just as capable. Lots of off road upgrades if you want.
Remember all D1's are at a minimum of 14 years old and originally came out in 1989.
D2's are likely the most common in your price range. They look similar to a D1, but share nothing (no components) other than a similar design language. The D2 is very good, but introduces more electronics and are a more complex vehicle as a result. But have the potential to be better on road than a D1 and better spec, while still very capable off road. 4.0 V8 and 2.5 TD5 diesel. Bodies don't rot on these, but the chassis can be more of an issue. The D2 is still a proper ladder chassis 4x4 with very good native off road abilities. But a lot of enhanced tech too.
A D3 might just be in budget or near too. These are a completely different type of vehicle. Vastly more complex and much more road focused while heavily using tech to make them capable off road.
