results from gambling and payouts have varied from patch to patch.
right now 1.10/1.11 i can tell you the payouts are pretty fair. what alot of people do not realise is that gambling for items is dependent on character level, there should be some info out there with exact calculations...but in other words dont go epecting to get an SOJ and level 10.
in the last current patches i think once i reach into the high 40's if you gamble strategically looking for specific items, or an item class populated with good items or that generate good magic properties more frequently you will be pleased. i would say i get a rare atleast from 30% of my tries. maybe 10% is actually really good stuff. these days i seem to be picking up lots of + character specific skill items and lots of MF items.
in the old days i used to pick up alot of nagelrings, manald heals, tarnhelms, steelclash, frostburns, magefists.....all set parts.....you get the idea. best find probably would be a silks of the victor.
bottom line...........GAMBLING IS AN AWESOME WAY OF GETTING GOOD ITEMS WHEN U PUT THE $$$ DOWN.