I was looking at the Platinum coins lately, since I think the Platinum price is the most undervalued one at the moment.
Australian 1oz Platypus or 1oz Maple leaf Platinum coins are even a bit cheaper than the eagle. However here in Germany we have to pay VAT on Platinum coins, which brings them up to about 1200 US dollars. Thats a long way to go before it brings any profit. But I don't give up the idea just yet... :)