HDR - similar situation as you. (i'm not maxed for contributions on 401 though). I also like the idea of wide diversity. Straight buying metals is something I don't do often - I generally combine it with other hobbies; usually coin collecting, but also different types of art. If you want to straight buy - the most popular searches are also the best in my experience. apmex.com and jmbullion.com are reputable, they ship quickly and there's no risk of something shady happening like some of the ebay sellers (though most of theose are safe too).
A metal bar or a metal coin are generally going to be the same price, so if you can get a coin or something you like, then it makes good sense to me. I have bought raw and graded on ebay, but I buy direct from US Mint if i'm going to get it cased/graded myself since you can almost assure a mint state grade. So, that can make it fun and a hobby for some and it's about the safest hobby investment there is.
