RENIX.., lol, hmmm... Yes I have a RENIX! If it were not for the experts on this site I would be hard pressed to diagnosis my XJ's electrical system. Very few scan tools remain in the world which can be "plugged in" to a RENIX system for diagnosis. Therefore for those of us unlucky RENIX owners.., we are left to the standby volt/ohm meters, of which.., both digital, and analog models are necessary. So far with 200,000 plus on the engine.., it's been very dependable. Renix was only available for the years between 1987--1990, I believe.
Therefore it is probably prudent to find other XJ's around, i.e., either get a second one for parts, or.., a long shot perhaps where you live.., find them in a junk yard. Yes you could find most of all the parts you need to maintain one from sources in the U.S.A., and elsewheres on the internet.., and too from some members on this site, (as well as other sites), that might be willing to kick some across the pond to you. I'd help on that, but I have great problems finding parts for my own rig in Alaska.
The lift, winch, snorkel, six wheels/tires, etc., are expensive additions so you probably are getting a good price. The price is a moot thing, as in 'relativity', lol.
One thing to consider is to inform everyone on this site more information about the XJ you are looking at. Is it a 2X4, or 4X4? Is it, (kind of an apple, and organge thing)' an automatic, or manual transmission? The tranny is a big issue as many would say that the Puke manual is prone to failure, especially when hard running with big heavy tall tires, etc., as well as hard on that year's narrow wheel bearings My '89 manual tranny is holding up just fine, but I do 'baby' it; such as maintaining steady rpm running through snow, or mud. I chose not to go above a 2" lift in order to maintain driveline angles of degrees within 'stock' allowances of variance so as to not prematurely destroy propeller shaft 'u'-joints, and also not to have to expensively modify the transfer case. In other words, you can more easily gain more efficient, stronger, less expensive to maintain, and ease of modifications if you go to a 'newer' model. Seems '99 is the most prized.., but even 'it' has it's issues.
I chose '89 simply because it was available, and I had a deparate need for a 4X4, and it has been very dependable for me, again through deep snow, and heavily rutted mud/water filled one lane country trail type roads. With this XJ, I would never take on highly articulated rock climbing, nor balls-to-the-walls mud churning contests. However, if you are dead-set on the '89 for fun, consider taking out the rear stabilizer bar, (cut it in two), and obtaining front stabilizer bar disconnects, (such as JKS), which will allow you to disconnect for trail issues, gaining an additional 3"-4" of axle articulations, (but remember to reconnect for highway travel). There are many other modifications that will enhance an '89 XJ that you can find to turn your rig into a competant one, (be sure to check the "Modification" section of
). Since the radiator coolant system is a 'closed' type, you might want to go to an 'open' type. However, if you mess with any aspect of the '89 closed coolant system just remember to evacuate air in the system by pointing the vehicle down hill and allow the air to escape by temporarilly removing sending unit close to the firewall. Other than some of the above issues with the '89 year model, you get what you pay for.., lol, and then some... Sort of like a boat where you toss money into a hole in the water, (in order to float, and motivate). Since the '89 is old you might want to use phosphoric acid to make all rust inert, and then paint over all such areas. If your windshield is pock-marked with tiny microscopic craters, you might want to find a replacement. The braking system can be modified by learning from the modification section to this forum, as the '89 XJ brakes are lackluster in performance, (keep your distance, i.e., anticipate).
BTW: Dzjens.., I am looking for a battery tray from a diesel XJ, and am prepared to deal with you if you can find one from some junk yard over where you are at. Please "pm" me if you are interested in helping me, and ofcourse there will be others on this site who would also be interested in that item, as a lot of us want dual battery setups and do not want to fabricate them for various reasons. Also, there is some more info. that is not often shared on any forum due to some reason, or another that you will want to know about the '89 XJ, should you buy it.
LOL--Welcome to 'our' world of XJ's.., erhh.., ahhh.., good luck!?!