The DX7 MKI has a special place in my heart... it was the first synthesizer that entered my home as a teenager. A family member who was a professional touring musician brought home a MKI one day, and it was the first prolonged exposure to a synthesizer I had up to that point. Like most buyers back then, we didn't understand FM synthesis or how to program it really, other than to mostly play presets and experiment without any real plan or method of learning. For younger folks who have grown up surrounded by softsynths or affordable hardware synths, it might be hard to relate to just how cool it was having that DX7 sitting there, available to me to play whenever I wanted, as long as it wasn't on touring duty.
I never actually owned one, although for a while I did own a TX81Z module. Since those times, the closest I've come has been software emulations like DX7V from Arturia and Dexed (I always gravitated toward the former, but it comes with the annoyance of resetting the velocity level every time you change a patch, which I consider a fairly major usability flaw. They defaulted to "DX7" to emulate the velocity range of an actual DX7, but it just results in a darker sound, so I have to change it to "FULL" every time I try a different sound. DX7V is quite faithful to the original on many patches based on my own recollection of those sounds). These are decent emulations but I believe Chipsynth OPS7 is better.
Chipsynth OPS7 (which pitches itself as a "bit-accurate emulation") does in fact seem to capture the original magic of the DX7 just a bit more than others I've tried. Not only do I prefer the preset manager (you can get all the original ROMs .syx as well as tons of DX7 patches with simple web searches), but certain sounds in the original ROMs seem to recreate the original DX7 sound better (I don't know if that's because the DAC has been emulated better or not).
But if you are a vintage Yamaha FM fan, this one is worth a look and IMHO worth what they're asking.
If you're opposed to softsynths, I relate completely when it comes to analog. None of them seem to capture true analog magic, IMO. But I am one who feels digital synths are being pretty well represented in software these days and are competitive with hardware counterpart.
https://plogue.com/products/chipsynth-ops7.htmlPros: Sounds better than Arturias *
Cons: Uses slightly more CPU than Arturias
* when I say "better", I mean on certain patches. On many patches in the original ROM, the two sound indistinguishable