Does Realtek offer a driver? Their site is confusing!
Repeating disclaimer: I have no first hand knowledge of this product/chipset, and the info that the product in question is using this chipset is based on a quick skim of some linux forum posts - in no way an official source.
Probably the reason that Belkin doesn't have a Win8 driver is that Realtek hasn't given them a baseline one to re-brand. According to Realtek's website, their last update for the 8192SU chipset was in 2012 and only supported up to Win7. Note that sometimes Win7 drivers will work in Win8 - depends on which driver model they're using.
(search for 8192SU on the page.)
If that one doesn't work and Microsoft hasn't picked up the torch, I'd guess that this hardware will never be supported under Win8, as there is little economic incentive for the manufacturers (either Realtek or Belkin) to do so at this point.
One more thing you could possibly try is installing the Windows 8.1 update (free update to Win8) which possibly has additional driver support. That said, if you can't reach the network downloading the update may be difficult.
Final thought - if all you need is a network card, you're OK with installing it yourself, and you've got personal transportation, you can quite possibly find one for free either by trolling through Craigslist posts or (if your municipality segregates electronics waste and you live in a well populated area) heading down to your local dump (I know that mine always has an assortment of computers in various states; usually most are fairly old, but if you're just looking for something equivalent to the above, it's not exactly new technology.) Of course, YMMV and all that, you may (will) end up with some dead ones along the way, and you'll probably need to take it out of an entire machine.