It's sad to see IBTanked having issues. They always had great service and reasonable prices. Just good folks. I went to their site Friday to order some replacement
tank glass for my KF4's, and saw that they were bare bones, and I wasn't going to get what I needed.
Fortunately, I found Spectrum
tanks online, and they were just as helpful as I was used to from IBT. Prices are a bit higher, but customer service comes with a price I suppose.
As far as carto's go, I was the same way for a long time. Had my brand, and nothing else came close. On a whim, I picked up an R91 when they were all the rage, learned how to rebuild, and haven't looked back. Not sure if it's helpful to you OP, but I do recommend rebuilding. The overall long term costs are far less, and there never a worry about finding your favorite.