Bit late getting into Big Finish - was tempted to start with their Sapphire and Steel releases from a few years ago, but couldn't squeeze them in - but their Survivors sets are very good indeed. Hope this run continues for a while.
Kinda tempted by their Omega Factor sets as well. Another 70s curio.
Never been tempted by their 2000ad line for some reason, and I believe that's now discontinued?
But going back to Survivors; I've got the first four sets, and I think the 5th is out now, or will be soon.