With BfA Azurite gear, I'd pick that over the exp buff for the trek through 110 to 120. Head, Shoulder and Chest. mind you that is 5k gold for each gear to upgrade to 120... so much gold. Next waste is for the Weapons upgrade. 100 is the max I should have done and stopped buying upgrades after that. 3k gold to get it to 110 and 7500 gold to get it to 120. Legion has you obtain the Artifact weapons for 100 to 110 so I use that over Heirloom gear obviously. And BfA has a nice weapon with better stats So I always pick that one as well.
My screenshot here is just of my cloth gear. I usually level Locks so I though I had to make all the Haste/Crit gear fully upgraded. Oh yeah and I also did all the plate because I have a Paladins and Warriors to level. Such an expensive mistake. I went there initially to get my leather gear upgraded for Leinaala my Druid, and I guess I just went crazy and I was getting excited having all of them turn gold when I got them to 120. I kick myself now because my guild bank dipped below 1mil gold. ugh, so annoyed! Well lesson learned.
So to end this....
the only gear I should have fully upgraded was Legs, and Rings. Trinks and necks are a waste because there is no exp buff for those and you can always get those while questing or running dungeons.
My bad... Never make that mistake again. I feel dumb. /cry