With this year Discovery it really just depends on how well the previous owner(s) took care of it. Discovery's can last 200k miles if well maintained BUT there are a lot of specialty systems on it so if not maintained repair needs can snowball quickly. The engines are pretty durable although if they are ever overheated they can sometimes incur internal engine damage that would require replacement or rebuild. At a dealership you can look to spend about $5k-7k for a replacement engine. Other high cost repairs to consider on the Discovery is the air suspension air struts if equipped. The air bag light can be on for two reasons, either there is actually a fault with the safety restraint system or it is on as a timed reminder to have the airbags inspected. The dealership can tell you if there is actually a problem with it by scanning it. For the seats, sorry I don't know of anybody in your area (I am in San Diego) but any upholstery shop should be able to redo the leather for a lot cheaper than just having the seat leather replaced at the dealership. The only dealer I believe that is in OR is Land Rover Portland (http://landroverportland.com/) dealers are a little few and far between unfortunately. Shops vary as far as their diagnostics, we are $135 in San Diego but everything is expensive here, haha! The good news is that when the cruise isn't working, it's usually just a bad vacuum line so the repair should be inexpensive.
I hope this helps!