That's right, the smallest HomeDepot carries is 1/4", which is way larger than you're looking for.
I would say a 10-24 2" bolt is your best bet, and you can find those at a local bolt/screw shop if you have one in your area.
Also , if that's not an option, another bolt you might want to use for a nice appearance is a Stainless or Chrome ButtonHead bolt. Those can be found at any Custom AutoParts shop.