First of all, you are asking on the wrong forum if you have a Range Rover. This is the LR4 forum, a car with a very different sticker price.
Secondly, these extended warranties are offered by many different underwriters, and are very much negotiable, as long as you are still under factory coverage. Call 10 dealers (and dealers are only one way to purchase these contracts) and you will probably get 10 different quotes for plans that may sound the same, but may not be - once you read the fine print. 7 year and 100K miles doesn't mean much in itself. Will you get a free loaner car, and for how long? Is there a deductible? Is it an exclusionary plan? And so on...
Obviously, all these insurance companies would love to get your money as soon as possible, knowing full well that they won't have to pay you a dime for a few years, and then they'll do their best not to give you any of that money back even after their coverage kicks in. That's what all insurance companies do, they wouldn't make money otherwise... I don't play that game personally and have never regretted it, but I fully understand people that do, because of the peace of mind thing.
However, you shouldn't get pressured by this snake oil salesman talk "If you buy today, I'll make you a special deal". The guy/gal/dealer gets a nice commission for selling you that policy, that's why he wants your check now. They are not interested in the least in saving you money down the road. In your shoes, I'd keep the factory warranty you've already paid for with your new car, and see how things go. If your car starts falling apart, you may not even want it anymore by the time the factory coverage is up, and you'd never recover all of that premium you paid years in advance if you sell it or trade it. If your car is super reliable, you may start wondering if paying $5K was such a good idea... IMHO, wait and negotiate an extended warranty if and when it's convenient for you, not for them. Extended warranties will always be there.