I am building on a budget and have frequently changed directions due to changing mission and changing budgets. I would recommend not making as many changes as I did!
Having said that, I would suggest that you can get it painted a single color for half or less what others are quoting or go with self-applied vinyl and reduce it even more.
You can get someone's last generation panel for $10-15k. I just sold my entire Dynon system with EVERY option including 2 screens for $10k because I am not going to be ready for it as soon as I hoped and didn't want to store avionics until they were obsolete.
There is archived evidence that you could buy a decent used engine and fixed pitch prop on this site for less than $20k EASY.
Finish kit is a must but you can buy the FWF piecemeal for half price - that's what I did - it just means more work for you. Take a picture of someone else's setup during their annual - it REALLY helps.
I would guess that I have AT LEAST $10k in all of the things that you don't really plan for, such as: seat cushions, harnesses, wiring, switches, lights, hardware, engine accessories, oil separator, decals, labels, throttle controls, stick grips, and on and on....
Summary: From your state to finish, I think you could scrounge and get by with another $40-45k and go up from there to another $150k. There is just no way to accurately predict. What I did was to plan for the next thing and start scouring the ads and airports WELL in advance of needing it. I also bought a great deal when it was available, whether I was ready for that part or not. That means that I ended up with extra stuff along the way as my plans changed but for the most part I have been able to sell the extras and get my money back.
I also bought an entire plane for the engine and sold the plane. An abandoned project for the tools and sold the project. Another abandoned project for the prop and sold the project. Traded my project for another project to get a finish kit. I have changed from a -6 (too much fabrication for me) to an -8 (wife not interested in flying) to a -7a (wife decided she likes flying when we are side by side) and now converting it to a -7 (to accommodate my preferred landing site).
Hope this helps!