Personally, I think the miles are a bit high for that price. If the truck was *well* cared for (full service records at a minimum), you could probably expect the engine *might* go another 50K. If the AFM / DOD is still enabled, be forewarned that that system is problematic (you can find posts all over here & elsewhere about it)
At 200K, you also need to be prepared to put some love / money into the trans. It's a pretty good unit, but at that mileage, again, I'd want to know detailed history on that thing and how the truck was used - if it had a life as a tow / plow vehicle, I'd stay away.
Now if it were a 2500, you could probably get another 100K out of it easy. If it had the diesel as well, even longer (but more $ for maintenance)
I often look online for 2003-13s, with under 150K on them, 5.3 4x4, ext cab. Older ones can be had for $5-6K; newer ones cost more, but dont have as many miles as the older ones do.
Finally, I'm guessing that's at a dealer - take a look at private sellers as well - they usually know a lot about the truck, and you get a better history that way.