Jjeff is right. These boxes are OK for OTA use, but they mostly suck for QAM.
The latest HomeWorXes no longer require a special firmware update for QAM, but they still don't support it officially. Mostly for the reasons
discovered: it won't work correctly with many clear QAM systems. How well one of these boxes works with your system depends on the combination of the QAM system itself, which channels you're interested in, and which firmware you use.
At present, your best bet for QAM under $50 is probably a $10 iView remote control, one of the iView firmware versions (V1 through V3) for the iView 3500STBII with a channel 3/4 switch, and (since iView no longer sells the particular box that ran those firmware versions) a new HomeWorX HW-150 to install the firmware on
(The eMatic might run the iView V1-V3 firmware also, but that hasn't been tested, and I don't know of a way to switch back if it doesn't work. At least you can get a backup copy of the HW-150 firmware from Mediasonic to revert to - as long as you don't brick your box
You'd have to try V1 through V3 to see which one works best for your system and needs, and it's still possible none of them will work very well
And of course Mediasonic could change the HW-150 hardware they're selling at any point so the iView V1-V3 firmware won't run on it anymore. And even if it all works, your cable company could simply eliminate clear QAM any time they wanted, wiping out your investment with no recourse.