This is a custom bundle, it should remove the games you already own and adjust the price accordingly.
I have 5/122 items and my price is 69.03 (91% discount)
True, but even if you already own stuff (and chances are you'd already own the most interesting games) it's still a lot, because although prices for individuals games look very cheap, there's a huge amount of DLCs that add up to about 45 EUR (or similar in $) despite the high discounts, and the great majority of that is cosmetic or multiplayer content that I would never be interested in buying on its own. So these DLCs actually even out the cheap prices on the main games to some extent.
(The anthology also doesn't include newer additions like LiS2 and Shadow of the Tomb Raider, but of course they would have raised the price significantly.)
It's still an insanely good offer, I guess, if you're really interested in the Tomb Raider, Legacy of Kain, Thief, Just Cause and Deus Ex series (and some other games) but for some mysterious reason hardly own any of them anywhere yet. All the games combined are definitely worth the asking price in that unlikely case. (Personally I won't buy 42 EUR worth of worthless DLCs though just to get some Kane & Lynch and a bunch of games I already have on GOG.) ;)
I decided to take a look at the DLCs, the following seems to add single player content to the game:
Deus Ex: Mankind Divided - System Rift
Deus Ex: Mankind Divided DLC - A Criminal Past
Dungeon Siege III: Treasures of the Sun
Just Cause 3 DLC: Bavarium Sea Heist Pack
Just Cause 3 DLC: Sky Fortress Pack
Just Cause 3 DLC: Mech Land Assault
Rise of the Tomb Raider - Season Pass
THIEF DLC: The Forsaken - Challenge Map
THIEF: The Bank Heist
Lara Croft GoL: All the Trappings - Challenge Pack 1
Lara Croft GoL: Things that Go Boom - Challenge Pack 2
Lara Croft GoL: Hazardous Reunion - Challenge Pack 3
That left 51 DLCs, totaling $108.49 US dollars. At 90% discount, you're paying about $10.85. I'm a bit surprised, I thought it would be a lot more.
The main reason I didn't pick this up was that I thought the DLCs were a lot more and if the games are on GOG, I already own it. I'm still not sure if the bundle is for me...