Dunno if "grail" is the right word, but I recently got this UC hoodie that I've been drooling over since it came out. Really happy with it and so stoked to finally own some UC because Jun is probably my favorite designer.
In terms of actual, seemingly unattainable grails though, mine is definitely this SLP sweater. Tried it on in an SLP store and fell in love, but I could never afford it new and I've never seen it for sale second-hand.
And this Raf parka, or similar Raf parkas. Never seen them in my size at a time when I could afford it.