I just replace the engine in my 2007 GS350, but it is no hybrid.
I did the work myself and found an 18k motor that a buddy of mine was able to get through his body shop for $2,800 plus tax.
We like the car and didn't want a car payment, so I am out around $3,700 for all the repairs including new hoses and a variable valve timing solenoid that was broken. (my 2007 had a different part number than the 2010 I put in.
Here are a couple engines that will fit, but you will have to pay labor if you don't do it yourself: https://lkqonline.com/2007/Lexus/Gs4...gine-Assembly/