In regards to TCM DVDs, I have 22 of 'em. 21 of 'em are collections. So far I have:
The Garbo Silents Collection (TCM Archives)
Garbo (TCM Archives)
Errol Flynn Adventures (TCM Spotlight)
UPA: The Jolly Frolics Collection (TCM Vault)
...and a good chunk of the Greatest Classic Films sets. The ones I have include:
Prohibition Era (Greatest Gangster Films)
War Collection: Battlefield Asia
WWII: Battlefield Europe
Yeah, I love collecting these. The Shakespeare one, for some reason, happens to be a rarity. Why that is, I dunno.
I have quite a few of the TCM releases too. I also own the Errol Flynn collection you mentioned. I also have the first two volumes of "Forbidden Hollywood." I also have the TCM Vault of William Powell & Myrna Loy as well as a Claudette Colbert set.
With the 4-movie TCM Greatest Film collections, it's funny, I don't think I have any of the ones you mentioned, except for Wartime musicals and the Prohibition Gangster films. Most of the sets I have are the actor ones.
With these 4-disc sets, I only buy them if I am interested in at least two of the films and I don't own a majority of the collection already. I love Errol Flynn & Lucille Ball, but I don't own their collections because I already have the films. I think I only ended up with a couple doubles when buying the TCM collections. I have 2 copies of "Swing Time." I also have 2 copies of "Baby Face."