More turbine stuff is showing up on FG. Their categories aren't broken down as much as RCGroups, but there's a bigger "expensive" plane crowd if you will? The last model I bought was a NIB T-One with all the goodies to put it together including the turbine from a seller on FG. I've bought primarily electrical stuff on RCGroups and not had any issues there either.
There are jet forums on each website, but don't amount to much right now but their gaining members with usernames I recognize from here on RCU.