@Kyle Donath,
I think @Nik Moushon is right about the $8k for permits, engineering, soils & survey being too low. By a significant amount. A surveyor coming from Denver will have travel time & probably multiple days of it. You might be able to find a survey company from Vail or Dillon, but I don't know what their travel time is or how busy they are in the spring. Something to think about. Also, it looks like Park county's online system doesn't need to be as robust as some larger, more populated counties. That is time to & from the county seat in Fairplay. And time spent talking to them, etc...If you're up there building anyway, it may not be too much of an issue. Again, just something to think about when building in margin.
A few things to budget for:
1. I think a big component that you can & need to nail down is cost of constructing on a site with plenty of granite. It invariably increases the cost & time of construction. I've heard of most mountain drilling being no less that $15k.
2. Remember that you're more than likely going to have to level out granite for both the house & the septic. With you designing though, you might be able to control these costs a little more.
3. Call South Park Telephone & IREA to see what it's going to cost to bring in the services. It'd be a good idea to have your house site roughly decided, as distance plays a role.
4. Heavy equipment rental will be a significant chunk of money. I imagine you'd have to rent it from down here in Denver. So budget travel to & from (I'd guess a day for each). And of course, whatever time on site you're going to need it. You'll have different types throughout the build. Excavator, Skid Steer (bobcat), Crane, etc...
5. Something I think that gets forgotten about, especially with larger mountain lots, is the driveway. Again, with you designing, it'll help. But you're going to have to lay asphalt or gravel from the maintained road up to your house.
6. I know foundation is included in the $200/sf estimate, but that's for Denver. Expect some increase in the bids that come in from you concrete sub, as they'll have to travel a decent distance to get to your site every day. I'd also call to see what the cost of a concrete truck delivery is for up there. For multiple pours.
I do not want to come across as though I'm trying to dissuade you. Quite the opposite. I see projects like this getting done up there & know it can be done, especially with you GC-ing & designing it. That will give you more margin than most. In fact, after all the time, effort & money you'll have into it, I'd bet on you having a hard time letting it go.