I wouldn't pay $90 for that car. I think it goes for $70, at best.
And it wasn't me that said he had ordered a 75S. We did chat about your car but I wanted subzero.
So, I'm still in the hunt.
Ah yes, I remember now. BTW, even in Chicago winters I found subzero was never a must have feature, but that's of course very personal.
Regarding which of the three options: I would rather spend that amount on a new Tesla, vs a used 90 with slightly more features.
So to share my opinion -since you asked for opinions
I would actually do a S100D in standard black (visually its a minor difference between the $1k Obsidian Black Metallic) with premium seats to keep its value. I wouldn't bother with the PUP (the standard audio is already amazing as is, subzero is overrated -unless you have frequent back passengers in the winter-, and hepa filter feature can simply be applied by yourself -see other thread about this)
And finally, since the full glass new roof has an amazing view, I would forgo the sunroof. The above shaves $8000 of the price.
Result is a Model S 100D for $97,300 - $7500 tax credit = $90k (vs $90k for the used 90D)
You will pay more in taxes though: IL private used car sales tax = $1500, buying from Tesla = about $9000.
So ultimately you will save just the sales tax difference for getting a new 100D vs used 90D. Not worth it. I would buy new.