Things to consider
If you know how to work on a Rover; Buy It.
If the delivery date of the vehicle you are interested still holds manufacturer warranty; buy it but get an extended warranty - not through Rover - unless you have the funds to pay their rediculous price.
If you buy and it still has manufacturer warranty, drive it trying your best to knock everything you can non harmfully off. Rover dealer will replace "everything" including trim pieces "assuming they haven't been knocked off due to abusiveness". They'll even replace or fix a torn seat. You name it, if it's under original warranty, it'll be fixed without cost, that is all things except wear items like brakes.
I've already had over $3,000 of replaced parts on my disco. My warranty just ended and I purchased an extended warranty through Royal Administrative. Try to buy your warranty before your manufacturer warranty expires, you will get a better warranty and a better price.
Keep in mind Rovers will have problems. An 04 is my choice vehicle, it's the last of a series and it's most likely to have all the kinks worked out. If you test drive and feel there is something not right, don't buy it. Or hire someone to look at it for you and offer to pay them $60 - $100 for an honest answer wheather they would buy it. They could also tell you what's wrong with it and how much your going to be putting into it to make it like new again. I had to replace my front drive shaft as the person I had look at it found that the front u-joints where loose. Rover replaced free of charge.
Put it this way, if you can find a reputable person who can work on Rover's that is charging $90 or less and hour and you can afford that kind of work and you have a warranty for major cost items, I would buy. This thing is different than the LR3, it's a tank. If you can afford $100 gas tanks everytime and the other costs, buy it and enjoy it. What a fantastic vehicle. There is nothing, abosolutely nothing like it on or off the road. If your excited to just get off-road and can't afford the cadillac ride of a Rover, buy a cheap Jeep.
Warranty - anything is better than nothing. There's a company called continental warranty that is pretty good. They all pretty much offer a warranty through Royal Administrative utilizing Lyndon Insurance as a back meaning you will always have funds in your warranty as long as the three business don't go out of business. These businesses have been around for over 20 years so they are whom I've went with. It cost me about $2500 and I've got a payment plan with zero interest for 18 months with the plan inaffect after 30 days and 1k miles. Research warranty companies utilizing the BBB. Don't look at things like rip-off report.com as anyone can post anything to that site making it non-reputable. My out of pocket visits are $100 and eveything on thwe warranty (which is alot) is covered free of charge. MAKE SURE THAT THE PLACE YOU HAVE YOUR SERVICE DONE ACCEPTES YOUR WARRANTY. In fact, have them look at the warranty and see if it's worth it. The guys in service told me it would be tough for me to personally out of pocket spend more than $2500 on parts and service in 5 years or less (the length of the warranty). For comfort reasons and piece of mind, and a lolt of research, I bought it. Again, it's getting late to buy an 04 with a warranty. Buy Buy Buy - or Don't. your choice... Or lease a New LR3 with a manufacturer warranty and don;t worry about it. I'd go disco, in fact, I went Disco...and it's great!