I think this is a starter. As noted before, some dealerships charge around $800. An independent garage with oem part may be around $500. You could probably get an aftermarket starter for around $200 and do it yourself. It would be worth you time to triple check your battery and connections before making a commitment to replace your starter.
I am kind of in the same situation myself. Over the holidays my 99 gs400 w/ 49,000 miles would not start - just got the CLICK. I initially thought it was the battery because it started with a jump. After charging for several hours in hope of resolving the issue, it would not start again. I took it to an independent garage that said the battery was dead. They also verified the draw was normal when the car is not running. After their charge it started perfectly for one month. Now it sits in my garage with nothing but a click.......
At this point, I need to get it back to the shop to test further an probably replace the starter. This seems to be a common problem, very disappointing