Quick look at Subaru.com says a 2011 starts at $24k. So they want 1/3 of the new price for a car that has 200k on it. Since the chances of it lasting to 800K miles is, well, astronomical, lol.....no, I'd pass at that price. If it were a couple thousand, maybe. This car has been driven a lot....5 years old and 200k is about 40k a year.
And mind you....my 2001 Town and Country van has reached about 270K and while it's still a good ride, dependable, I wouldn't dream of paying $8k for it...and I think we bought it new in the mid $20,000 range too. And as you can see I drive my car about 30k a year.....and I feel like I drive A LOT compared to the average person. I'd definitely want to find out what kind of driving this vehicle has had....being that mine was a van, it's all been roads of course, but the Subaru.com pictures look like this vehicle may have a bit of off-road which is harder on everything.
If you do want to consider it I would pay a qualified mechanic to go it THOROUGHLY and give you an opinion of how much longer it will last. You'll have to pay to get a truly thorough review, but it will be worth it to not spend that kind of money and find out in a year that you blew it!