In reply to Calum Nicoll:
My three penn'orth for what it's worth (based on a some overlanding experience both in North America and Africa.) First of all, well done with your plan for a proper DIY adventure. It should be a very interesting trip.
OK, some thoughts:
I think your vehicle budget is too low - as in your minimum budget needs to be £5K. £2K for a 4x4 for a trip such as this is simply too low. Basically you trade one cost for another. The less the initial purchase price, the more you will need to spend to try and ensure mechanical reliability. In addition, you'll need 6 all-terrain tyres (2 spares) and don't skimp on these - go for the likes of BF Goodrich or General Grabber. 6 such tyres will cost £700+ (which puts your £2K budget into perspective!)
Whatever you'll get is going to be very cramped for 5/6 people. The suggestions re. getting a Merc Sprinter 4x4 van (or even a VW T4 Synchro) are excellent and would give you more space and comfort but, unfortunately, your budget's too low to go down this road. 5/6 in a single 4x4 is going to be a struggle to say the least and personally with that number, I'd be thinking straight away of 2 vehicles with 3 in each..
There is the argument that you first of all choose a type of vehicle (eg Toyota Land Cruiser, LR Defender) then budget for a total mechanical overhaul. Once you've done this, you then go out and try and buy the best vehicle you can for the money you have remaining. By doing it this way you hopefully end up with a vehicle that is a known quantity. Also bear in mind 5/6 people, plus luggage. How much weight [including passengers] are you going to carry (spare tyres, water, books, food, clothes, extra fuel] around in your vehicle? 500kg? 700kg? 1,000kg? More?!
I would suggest that you buy a vehicle that is as standard and as basic as possible and then bring it up to the level of modification needed for the trip. You may well get away without needing a suspension lift. Personally I'd keep the suspension height as standard but fit heavy duty springs and uprated shocks. I'd then fit sump, fuel tank and diff guards and that's it. Keep it as simple and as standard as possible. You can live without A/C.
If you were going to Africa, I'd choose a either a Toyota or a Land Rover 300Tdi as a distant second choice. However, you're going to Central Asia, so I'd bin any notion of buying a Land Rover straight away. Every capital city in the countries you'll travel through will have a Toyota garage so I'd go for a Toyota if you can. Land Rovers are virtually unknown as local vehicles in Central Asia but Toyotas have been used there for years.
Diesel can often be hard to find in the Central Asian boonies. Do your research and it may make sense to go for a petrol 4x4. Otherwise add the cost of fitting a long range tank to your diesel 4x4.
Remember to allow for the cost of a carnet. Research this carefully as vehicle carnet prices for some countries are based on the purchase price of the vehicle.
So, finally, allowing for the limitations of your budget, what 4x4 would I suggest you get? A Toyota certainly, but not a Land Cruiser (beyond budget). No, I'd get a 1990s Toyota 4Runner, which is basically a Hilux but with space for 5. It's a sensible choice; cheap(ish) to buy; diesel or petrol; minimal electronics; leafsprings in the back; solid axles.
You may need to, er, junk the 6th person!
Hope this helps.
Dave