A KKTO, Coretto or something similar are really your only budget options, but you have to be happy to take on a project obviously. A Coretto is probably the simplest and cheapest to build, and I believe you can get bread makers big enough to roast close to 1kg at a time. It sounds like what you really want is a Sonofresco, but you don’t want to pay that much. Unless you’re in North America I’d actually recommend a Behmor (the 220v version is superior to the 110v). The 1600+ is much improved over the old 1600, and not just in functionality either. I’m sure that if you cared for it as recommended you’d get good service from a Behmor. I’ve had my 1600+ for over two years and have done 200 roasts on it. I clean it religiously after every 5 roasts and keep it under a cover in the garage. I’ve had no issues and it’s working as well today (roasting as I type this) as it did the day I opened it. With the years of experience you already have I’m sure you’d get great results once you familiarise yourself with it again.