The Hero uses a 'Mini-B' USB port, usually just referred to as 'miniUSB'.
Note that this is not
the same as 'microUSB', which the Samsung Moment and other new devices use - this is a much thinner connector than the Mini-B
Most digital cameras (the point-and-shoot kind), external USB harddrives, etc use this type of connector, it's fairly common. As such, I had several just 'laying around' to use. One plugged into the wall adapter next to my bed, one plugged into a USB cigar-lighter adapter in my car, and the HTC supplied cable I bring around in my laptop back for work and elsewhere. My girl did the same for her Hero, and i've still got a couple lying around.
I can't say anything for the monoprice site, never used them, but I wouldn't pay more than $5 for one of these cables. They're ubiquitous. So common, in fact, that I bet if you asked 3 friends if they had an extra hanging about from some old device they never use, you'd get one for free
If you do buy, the 'ferrite core' isn't necessary, but is usually wise. this is basically a dampener to reduce the 'noise' over the line. Great for data transfer, but doesn't matter much for power transfer. I wouldn't buy from places like BestBuy, RadioShack, etc - extremely
overpriced there. Also, regardless of whether or not you think you'll use the USB mass-storage feature, make sure you're buying data
cables, and not just power
cables. The rocketfish-brand 'charging' cables, for example, are not
data cables. Made that mistake myself. Generally, if it's not labled 'charging cable', it's usually a data cable.