A couple things to consider:
- Are they modified to only use either the 0dB or -15dB attenuator barrels and no longer utilizing the larger "bodies"?
- Are cardioid and/or omni capsules included?
- You mention all the cables - how are they terminated and does the set include a dedicated power supply?
If absolutely everything is included, the value may range from $400-800, but in reality it's whatever someone is willing to spend. These sets rarely, if ever, come up anymore. I owned a modified set some years back that utilized the -15dB barrels, terminated to p48 adapters/XLR, and had omni/card capsules. I'm pretty sure I sold it for around $500 or so, but can't recall the exact value.