I'm certain it is a buyer's market. The IS-F is a tough car to sell - so I'd ignore the advertised prices.
Here's some cars that have gone to market in the last year. Only one of the three has sold, and that took 5 months to sell.
I can save you the time assessing the NX.
Here's my in depth review - "An NX hybrid would struggle to pull the skin of a rice pudding"
There you go - job done.
Do the maths -
1. Best colour
2. Previous owner loved that car
3. FULL Lexus service history
4. Spanking new steering rack - so no need to worry about the IS-F steering rack design fault.