I would classify it as being a rare...
I have personally fished up over 300 SOS and haven't gotten one of the barnacle covered grey ones.
but I have gotten two of the grey metal ones.
both of those I didn't get on TC, when testing... so that's why they weren't in the pics I posted.
If someone wanted a full collection of the recovered from a shipwreck collection, there is no telling how much they would pay.