It really depend where you live.
For example here in Brazil, a decent touch screen cost many panels (if you discount time to invest).
I am myself building slowly my pit.
Have a non touchscreen for gauges.
Some switches and buttons, (pan to add more) but not a replicate and not full stuff.
I want it to remain generic to be able to switch between Sims in a practical way.
So mindmapping switch group and switch position by relevance is important to avoid the "activating the right thing in the wrong place because in a diferent sim" syndrome.
Or the "Damn now i have all this stuff positioned and it ain t pratical for no sim but one" problem.
First thing to do for a cockpit is, let hype go down...then start to think clearly.
What kind of display, what kind of controls, what space do i really have/need ?
Fully replica (in any of the case) or flexible generic config ?
speadsheet what do you want and categorise in Critical(In my case it was: Must fit in the reserved space, must have big screen (or 3 normals), must be confortable (even to work) and must assent HOTAS in a confortable way 9without them getting in the way), must be done quickly to not render computer unusable (used for work) and must not pass XXX money unit), i really use it (XXX switches and XXXX buttons, MFDs), would be nice to have(I, for example, would like a UFC and a warning system....but i am totally unable to find any company able to do them at even a reasonable price (just need faceplates.) the rest i can manage.) and dreamlike (full generic cockpit).
Once listed, add estimated prices for each component involved, add estimated time for each component involved.
Then let it sleep 48 to 36 hours, when you come back things will have matured, Then review your list critically.
Remember, the most important is what you really use.