I just got a 2002 SC430 3 weeks ago, I found it on Autotrader.com. I got it from a Lexus dealer, certified 100k warranty. It was $51,000 but I talked them down to 48k with 18k, like new. It's Pearl White with Saddle Interior. I love the car, it drives like a dream, I get alot of compliments on it. I'll post some pictures later this week. I didn't like the stock rims, so I got these:
If anyone is looking for stock SC430 rims I'll sell mine for $200.00 plus shipping.
as for buying tips, check ebay daily, great deals, as well as AutoTrader.com. Try to buy certified, they give you the car like new plus warranty for 3 years 100k miles.