Hi Michael,
We’ve spent quite a bit of time talking to the Subconn folks as well. The $120-$150 range is about what you’d have to spend to get an 8 pin connector from them. If you’re using the Advanced Electronics with the Fathom-X board, then you technically only need 2 pins in the connector, which can reduce the price substantially.
Most pro ROV tethers that I have see use a polyethylene foam jacket. The only problem with it is that polyethylene doesn’t adhere to most potting compounds very well. We’ve had good luck with sealing the tether in our cable penetrators using a few different types of epoxy. We’ve also tried adding a length of heat shrink over the tether first. The heat shrink acts like an O-ring seal and provides a better surface to adhere to.
We’re planning to have a suitable connector available within a few months, just FYI.
-Rusty