I had to open more than 600 lunar fortunes before I got one, just when I was about to give it up not having anymore characters for the quests.
I found it very irritating and most of all very, very boring but I'm also very stubborn too! :P
Next time I'll be buying one and spend my time in a better way.
I did all the quests on 14 toons, and ended up using 556 fortunes before the Ox appeared for me, so no not common. But I know my Guild Leader opened about the same number and had 5. I REALLY REALLY wish I had that amount of 'luck', even if it's only occasionally instead of never.
I think it is random. I opened about 250-300 fortunes, no ox (bought one). Last year I opened 250 fortunes, got my rat on the 100th one.
So some people will get a lot of them and will brag. Some will get none and will say nothing. I think the drop rate is probably the same. The people that brag how many they are getting are probably just lowering the price. Although I probably paid more than I needed to (27k, and I heard of them going as low as 20)
Last year I did the quests and got fortunes with all of my available characters, and no rat showed up. So incredibly frustrating and pointless, especially because minis don't do anything useful. (But I still wanted the stupid thing!) This year I didn't really care or expect much so I decided to just run through the quests with one character-- my survivor, for the 5,000 XP per ten-minute quest-- and get what I got. I opened up all the fortunes at once, and I actually got an ox halfway through! Really surprising. I ended up doing the quests again with one other character and didn't get anything out of those. It seems like everyone's luck this year is about the same as the last. Blargh. I also missed the first (2007) new year event altogether because I'd stopped playing at the time.
6th fortune - celestial ox (then used about 50 more)
on monday morning (before going to work) with my last lunar token (left over from red bags), went to hochei, /paper, won, went outside and boom ! celestial ox again
I think I'm gonna have a lucky year
2nd try got one, then got my second at about try #15 (yes very lucky but I was born in the year of the Ox). I had about 40 more, no oxes, but I only wanted one for myself.
1 in 350 fortunes, definitely reachable (but if it wasn't for the last batch of 36 on Sunday, and I think it was among the last 6 fortunes, I wouldn't have gotten any).
I did every quest on 5 characters, along with buying Lunar Tokens, and selling my party points to get more Lunar Tokens, and ended up getting 5, one of which I gave away.