KUL has allegedly stated that they are replenishing supplies. This was about 6 weeks ago, though nothing has shown up in any of the places that have stocked them, at least in N. America. As to any sort of collectability - put that thought out of your mind. The Realforce 10th Anniversary edition is about the only mass-produced keyboard of the last 5+ years that could even remotely be deemed collectible.
It's funny because I actually have a 55g Realforce and a Cherry MX green CoolerMaster Quickfire Rapid on their way to me. I've used 45g uniform and variable weight Realforce boards and liked them both, so I'm very curious to try 55g. On the Cherry side, I have unusual preferences in that I like both their lightest and heaviest switches (red, brown, green) but not the ones in between (blue, clear).
Overall, both the Realforce and KUL are solid choices. Not sure what the price difference is between them in your neck of the woods, but at least in the US, it's about $100. Even still, I'd probably give the edge to the Realforce.