I don't think the factory does "chrome" wheels for the IS300. You can get "Graphite Polished" wheels as an option - they have a different finish than the stock wheels, but it is not "chrome".
Many dealers will contract with 3rd parties to add chrome to the stock wheels.
From what I have seen the "aftermarket" chrome wheels (with dealer markup) cost $1000-$2000 over the regular price of stock wheels.
The factory "graphite polished" wheels are a $400 (MSRP) option.
California wasn't getting any graphite polished wheels at first, but they are starting to show up in limited numbers now.