I got 72,000+ hits when I put "headset microphone" in the IE address bar (MSN search). Both Office Depot and OfficeMax showed up on the first page, and CompUSA was there in the second 25 or so, if you're looking for a local source.

You might take a look at CNet Shopping, which came up on the first page. You can click on "check prices" for any that looks interesting and get a (usually long) list of places that sell that particular one. Sometimes the individual "seller sites" give pretty good specs, as well. (Not a recommendation for CNet, although they're well known. They just came up first. You'll find similar at ZDNet, or several others.)

You would likely get very similar results searching for "boom microphone," but it would include lots of stage-scale stuff along with desktop stuff.

I noted that several of the "hits" on that quick-search were for mobile/cell phone stuff, so a look at your local cell phone shop might find something you'd like. And there's always Radio Shack...

John