Hello SM91 and welcome to the nut house.
One of the suggestions I make, perhaps reading too much into your post, is try not to worry until things actually break. The fact you've had to replace the chain and fork seals just means they are new and should be good for a few years. This doesn't mean the big end is about to go and the swing arm fall off. What's the worst that can happen? It breaks to the point it'll cost too much to fix, you are on the bus until you can pick up another one. It's as easy to sell the good bits of the wreck as the whole bike on e-bay and there are always plenty of old but MOT'd bikes on e-bay. The whole advantage of old simple bikes over 18 month old BMW's is that push comes to shove you can just break it for parts at little loss compared to selling the whole bike.
Enfields are odd. Half the owners don't actually ride them, they dress them up to look like Goldstars or Triumph Trail bikes and they change the oil. They mess with the valves, change the oil, fit AMAL's, change the oil, rejet the AMAL, change the oil with the result that they have three year old bikes with 3000 miles on the clock that they've spend the equivalent of a Goldstar on but are still 18.2 HP and have run for hours trying to prime the oil circuit. The prices prices reflect what the next guy will pay to do something similar. I enjoyed mine when I had it and would have another, but when you only have space/cash for a limited number of bikes, these are pretty limited. You can take a Rotax engined whatever on the back roads and enjoy the power delivery, you can't ride an Enfield on the motorway to get places in a hurry.
Andy