In that application, I wouldn't go the clip on route. Clip ons are (mainly) omni mics and, because of the distance from your mouth, tend to pick up a fair amount of room noise.
Instead, I'd consider a headset/over ear mic.
At the cheaper end of the market,
MICROPHONE MADNESS have some very good mics around/just over the $100 mark. I'd go for a cardioid/directional one and choose either the single ear or dual ear mount depending on what you're comfortable with. Note that you'll also probably want their battery module to power the mic.
At the high end of the market, it's a toss up for me between
DPA and
COUNTRYMAN. Both make excellent mics and I've used both brands with excellent results, depending on the exact project. Note again that you'll need to consider what you're plugging into and will likely need some kind of battery pack/power supply. Sit down before looking at the DPA and Countryman price lists though!
There may be cheaper options out there but I don't have personal experience of any of them.