Lost count of the mats I've spent tryiing to get an in-geom this season so I feel your pain.
Gave up on farming Saturday night and went back to rifting got to to GR74 - once I complete GR75 I'm done with the Season Journey and I'll go back to Hard core like I normally do. Just going to farm two Caldesans to make the push to GR75 easier.
If you neeed to farm DB you need a fast build - such as leap quake - if possible with Sage's (crafted set that gives an extra DB whever one drops). not up on the current speed builds for Barbarians but Reddit etc is bound to have one - good thing is a T10 speed build is usually much easier to get than a GR build (normally you just need the right items not well rolled ones).
I don't have the fastest possible farm build for wizards but I can do 3 min T10 pretty consistently - get in a 4 man group and just farm keys and mats.
DinAlt
The reakor build is fairly fast, like I charge so many mobs get a full fury and drop a boulder on them its usually insta kill on small gold and blue mobs, the problem is the lasesr and the explosions and the ice explosions and and the ice torando, I usually die instantly anything beyond tor8