I mulled over this forever as well.

I ended up not getting the extended warranty, and at 50,500 miles my right rear brake caliper seized up.
Luckily my local dealership is great and even with out being out of warranty (so close), they ordered a new caliper and fully replaced it at no charge.

So far so good since then... (knock on wood).

 

they told me $2375 for the 3 year extension to 100k. For $1600 I'd take it

 

$1,600 sounds pretty reasonable. I'd go for it, but only if you're planning on keeping the car for another 3 years.

 

Personally I plan to get the 8 year warranty then sell it after I've owned the car for 7... figure it'll help resale a fair bit if I can sell the car with a full year of warranty left on it.

(the Lexus extended warranty is transferable once)

 

if you have a is350 and had the valve spring recall, they give you a 6yr 100,000 mile power train warranty. Not the greatest but it helps...