Most straightforward way to buy T-bills?

[Ted King]

The subject header pretty much says it. I've got a fair size chunk of money I've decided to put into Treasury Bills, but I'm not sure about what the best way is to get them. Are there usually fees involved that you have pay someone to purchase the bills? I called my credit union and a local bank where we have our safe deposit box and account for our mortgage payment, but neither of them sell Treasury Bills "over-the-counter".