I'm pretty new to the world of the 100 series, but I can share what little info I've learned here, and from working at a car dealership.
First, depending on where you live, don't listen to what anyone from the south or west says about an acceptable amount of rust. Those guys never see rust and panic at even tiny amounts. Here in the northeast, even plastic rusts a bit. We deal with it. Rotting is bad, rust can be dealt with. The body souldn't be rusting, but in my area, the undercarriage will have rust.
Second, in all reality, the LC/LX are some of the most reliable vehicles on the road. But if you only read forums, you'll see a lot of problems. Well, that because people only post when they have problems. And, people frequenting forums are only a small percentage of total owners. What I'm getting at is even though no one ever posts "hey guys, just wanted to let you know my Landcruiser is still running great", the vast majority of them are. According to most sources, Toyota/Lexus make the most reliable vehicles on the road. And, the LX/LC maybe the most reliable models made by the most reliable brand. That's not biased fanboy talk.
Third, it seems to me as a newbie that the AHC thing is mostly blown out of proportion. If you search this forum for "AHC", I'd wager you'd find far more posts from people worried about the AHC than from people actually having problems with it. As long as it's taken care of, it seems to have a very good chance of lasting a very long time. If/when it does fail, you can replace it with non-AHC suspension.
Fourth, Timing belt. This does need to be done. But it needs to be done on virtually any timing belt equipped vehicle by 90,000 miles. In fact, I can't prove it, but I seem to remember some of my cars in the past needing it at 60,000 mile intervals. So, yea, it's a possible expense, but not one thats unique to LC/LX.
Fifth, price. Don't bother. In my short time here, one of the most common questions (besides AHC stuff) is "How much should I pay for this..." One member put together a formula that averages asking prices. That took math skills and patience I can't even comprehend. Bottom line is, don't get bogged down it what other people think is a good deal. Get the right vehicle for you at a price you feel the market in your area will bear. If you post a value question here, you'll likely get several answers ranging from "That's a fair price if the timing belt is done" to "That one has AHC, I'd throw garlic and holy water at it and run away" to some guy from Arizona asking what the tiny spot of brown stuff is on the corner of a bumper bracket. In my area, they don't come up for sale often. It's not like shopping for a Honda Civic or a Jeep where theres one for sale on every street corner. When you find one that looks decent, check whats for sale on Cars.com, craigslist and wherever else and decide if the seller is asking a fair price. If he is, and you like the vehicle go for it. Again, these are reliable. It's not like Yugo (remember those?) shopping where you have to cross your fingers and hope you get the 1 out of 10 good one. Even a high mileage and beat up LC is likely going to be more reliable than a new Fiat.
Just one new guys opinion.