Yes, that is an RF modulator for ATSC digital TV. It will convert one video and audio source to the digital channel you choose.
Use "ATSC modulator" (no quotes) as your Google search term and you'll find more hits. However, not all of them can handle HD, so check the reviews. You may also want to try the AVS Forums that pop up on that search. The people who frequent that part of AVS may have more knowledge of ATSC modulators than this HDMI forum.
Also, you're probably still looking upwards of $500+, which is much more than I would pay for repairing sheetrock and repainting. If you are less than 25 feet distance between the devices, HDMI or component would still be cheaper (assuming you are allowed to break into the wall). However, if you go HDMI, you should research how an HDMI splitter would work - only one type of signal can go out to all TV/monitors and all of the TV/monitors have to be compatible with that one type of signal for the splitter to work correctly. Check the archives of this forum for more discussion of "lowest common denominator" if you decide to open-up the wall.