Before spending I suggest to have a look at the Qudelix 5K.
Not quite as comfortable as the Cipher (extra little box) but more flexible - and more power for those wanting (not me).
At least it’s price-point relativates asking prices for Cipher.
AUDEZE doesn‘t list the original Cipher any more, but might be worth to ask them.
The Cipher cable turns up quite often in private sales, only make sure you get the right one:
• EL-8 and Sine, open and closed, use the same Cipher Cable, with the 3 dB bass boost only.
• The “i...”-designated ones, like iSine, have very strange pre-EQs.
They have different connectors too, that don’t fit.
There have been 2 hardware ”generations”, both have their own iPhone apps, which are still available.
A search for Audeze El 8, or Audeze Sine, will reveal some, e.g:
https://www.ebay.de/itm/125224252652?hash=item1d27f274ec:g:XVIAAOSw8kRiPuEs