In Episode 1x19, a couple Ferengi manage to stun (almost) the entire crew of the Enterprise NX-01 and board it wearing gas masks to steal valuables:
We see the four Ferengi dock with a pretty pathetic little ship and loot all decks basically grabbing everything they consider remotely of value (including chairs!), plus a couple of crew members -- apparently to sell as slaves.
At any rate, why don't they just take the entire ship? They're probably not ruthless enough to just kill everybody; But they could search the ship for all crew members (I think they have technology that is sophisticated enough to detect life signs, right?) put them in escape capsules / shuttle pods / whatever, and then just steal the whole ship, including all its valuables. The ship itself is probably worth more than any of those Ferengi could heist in their lifetime. Additionally, they'd have all the time they need to find that elusive vault.