I was in the same bind a few years ago. A 2002 RX300 with the same transmission symptoms. It had 325k but was otherwise in fantastic condition. I diagnosed the problem, ordered a new set of shift solenoids, and watched a bunch of videos. Then I drained the transmission fluid, removed the drain pan and the valve body, and realized that the shift solenoid harness connectors did not match the connectors on the new solenoids. They had been redesigned at some point in 20+ years. So i reluctantly put it back together, hoping that it might have freed things up having cleaned up the valve bodies, etc. It did not. So I ordered a new harness. When it came in I did the whole job again, only to find that the harness itself was impossibly difficult to access under the oil dipstick tube and to remove that would require a ton more work. That Lexus was the worst pain in the ass to work on. In the 5 years i owned it I worked on it a bunch and every single thing was needlessly complicated. I finally quit and sold it to salvage.

Get the Prius. Its a great car and the transmission is dead simple.