Essentially how much are you willing to pay. All the cheap figures you have been told are probably based on the idea that people have seen cheaper cars and therefore told themselves that if they have seen one truck that cheap they aren't going to spend more. You also have to ask the question. I can buy a cheap truck for £1000, then discover that it actually does need to have £1000 spent on it to get up to scratch, along with the time its off the road being fixed. If this one is as tidy as you say it is, and you bargain them down to £1500 and its a little gem then you have saved yourself £500 and a load of heartache and grief along the way.
Cheap vehicles that don't need anything done to them are very few and far between. I am of the opinion these days that I would rather spend the extra pennies and get something that I can just get into and drive without the annoyance and hassle of having to fix it once I have bought it.
Looking at the photo's it certainly looks tidy enough (without actually seeing all the masses of areas that could contain issues), and you say it runs and drives well. Now compare it to any other 4x4 (Isuzu Troopers included) and your not going to get anything else pristine clean, running sweetly, and available for anything less than £2000 (Discovery's probably twice that).
If it were me and its immaculate as you say. I would offer £1500 cash (as I would need to find the money to tax it before driving it away r.e. new car tax laws) and consider it a good deal.
Another thing to consider folks is the OP is looking now. Does he have the time to spends months looking for that gem of a truck we keep reading about. Possibly not. He/she has probably been looking for a while now and has seen this and taken his/her fancy
Westo. If your unsure about anything on the truck, go have another look with a friend with experienced eyes to make sure. I did this not so long ago with Bobbinsjob over a Tigra I was looking at. he spotted a few things that I missed which were deal breakers.