1. A Discovery is not to be viewed as a stable investment. D1s in running condition are easily under $2K in many areas. D2s can be had well under $5k in many areas. Yet these vehicles once had high sticker prices as well. People continue to operate them and repair them because they are unique, fun, and useful.
2. D1 and D2 are easily DIY maintenance. LR3 has more things (electronics) that require dealer level diagnostic tools.
3. D1 & D2 have tons of optional aftermarket stuff availabale, bumpers, winches, roof racks, etc.
4. Download a copy of the RAVE service manual set (link below, free). Look at some of the service practices, and see if they look like something you could tackle. You would have to purchase some tools, and you would need a place to work. While you don't have to have the experience of installing a Zeiss SEM or TEM , it helps if you can use a cell phone, open a beer can, and crawl under the vehicle (curses are optional). Meaning that thousands of mechanics have less understanding of physics, organic chemistry, and logic than you, but they have experience of having done it wrong a few times.
5. You are in grad school, so that means you have to eat grad school chili, work long hours on the faculty grant requests, even longer hours on your own research, and funds will always be tight. So my advise is to purchase a usable D1 or D2 and use that to get you through to the day you defend. (After you defend your dissertation, your income may rise to where you could get a Defender; but that is another dream - and quite possible if your return to India). You do have to balance the idea of how much time you can take away from your academic work for chores like changing oil, water pump, etc. But if you have it done at a dealer, the costs skyrocket. All Land Rovers require service, they are not oil change and tires kind of vehicles. Would avoid Freelander at all costs.
You can use a search tool like
www.statewidelist.com to seach all of craigslist in your state or nearby states. It lets you input "rover" and price ranges, and dealer and or private sale. The output is by metro area. Cal is covered with them.
You would want to have basic mechanical skills to deal with minor problems that seem to pop up (or drop off) when off road, regardless of vehicle brand. But you don't have to be in ME to work on, enjoy, and safely operate an off road machine.