OP asked what is your grail, then asked us to share our "Most priced sneaker" ? Sounds like two different things to me.
-- My grails will forever be the Black-Cement III and the Black-Cement IV. If I could only wear those 2 shoes for the rest of my life, i'd be more than content.
-- As far as my "Most priced sneaker"... that's an MJ autographed pair of Metallic Vs I got him to sign at a golf course in Scottsdale, Ariz. several years ago. Dude was druuuuuuunk... but he was cool about it.