There is one supplier that carries them.
https://www.canuckhomebrewsupply.com/collections/brewing-equipment/spike-kettles
I havent bought anything from theese guys though.
Racked my brown ale that stalled out at 1020 to secondary, added 2L of 1020 wort from dme to get volume up, and added some dregs from a couple krieks i had drank and some lacto.