@woodchucker The domestic ones here were also very expensive. I bought one, at I think 40$. The locking cable guys were the only ones i know that use the same lock. The connector was rated at 80lbs (!!). I'm sure original guys are out of business now. Just too expensive to make, and too small a market.
An alternative is is to make a board or plate that will put a bend in the cable of about 90 degrees with a hole for each wire. So any pull on the wire has to overcome the friction of the bend. I'll try to sketch something out this afternoon if you are interested.