Got it...
It is not an overly complicated plan. I think you have a number of options to lower the cost impact:
1) You could build it in stages, adding turnouts and sidings as you are able. Start with the basic loop and one run around, and then add the sidings as you go. This should be fairly easy with Unitrack, but you will have an "unfinished" layout for some time.
2) Simplify the plan permanently. Eliminate the "top" run around, and one of the sidings inside the loop on the left. That removes three of 8 turnouts. Funcationality for operations is reduced, but not eliminated.
3) Choose another plan...!
4) Use different turnouts and track. This layout would not be hard to replicate with other turnouts and track, such as Atlas (probably the least expensive servicable, decent quality track). Flex track will definitely save you money over sectional Unitrack. You can further reduce the cost by laying the track directly on the subroadbed (plywood, foam, whatever) without the cork or foam roadbed. Whether this is acceptible is up to you - it does alter the appearance significantly.
Even going to Atlas "snap track" and "snap switches" (basic turnouts) would save money over the Kato Unitrack. Atlas makes a "starter" set that you could add extra track to in order to approximate the Carolina Central.
Good luck. Hope that helps...!
Andrew