if my Battle Preparations gets defied but i showed off a gear, do i still get 2 runes

No — if Battle Preparations is Defied, you get nothing, including no 2 runes readied. Show Off is not a cost that pays for a separate benefit; it just flags whether the spell's resolution applies the rider. A countered spell isn't considered played and none of its instructions execute (CR 426.1), so the +2 Might and the rune readying both fizzle — same as any other spell hit by Defy (FAQ #11277). The revealed gear stays revealed, but it buys you nothing.