Coin shows and local shops too, depends on where you live. Here in my part of Michigan gold US Eagles carry a premium but not too bad.
When I visited friends in Northern Colorado the premium on Eagles was ridiculously high.
You can do OK buying from big name dealers on ebay too. Good Luck!
I did get some of these early on but like Muji said, the premiums are high on sub ounce gold coins. Since I only collect bullion and not graded coins I think of gold as a bank account and the silver as a checking account. Anything of metal value under an ounce that i need I can use silver rather than gold.
If you want some fractional gold, you might look at stuff from Europe. British sovereigns, German 20 mark coins, any European 20 franc coins from France, Belgium, Switzerland, Italy, etc.. All of these coins give you gold in the .18, or .23 range for a modest premium over spot, as a general rule. I like them quite a lot. As Muja says, try places like Apmex, on their web site or even eBay. They are reliable and always send me decent stuff for my money. There are other reputable dealers, also.
If you're gonna go the 1/10 route and not completely sold on eagles you can usually find some off brand 1/10 deals on eBay with ebucks like the pearl harbor 75 anniversary, Devils Brigade commemorative, The new Perth lunar, etc... That will be a little cheaper.