BuyPlatinumCoins.com
These days, with the shaky economy, more and more people are turning to precious metals as an investment. Platinum might not be as popular as gold/silver, but there is definitely a market for it (platinum coins regularly sell for $1000s on ebay). Needless to say, this domain is perfect for anyone working in the platinum biz.
Domain is 4 years old and currently at Moniker.
Hit me up if interested
