I have 1077 quests completed on my Monk. I did:
19 quests in BC
~20 quests in WotLK
37 in Kalimdor
136 in EK
65 in Panda Starting Zone
~50 Dungeon Quests
~50 Miscellaneous
So 836 or so is what I did it in. I was a monk so I had extra XP for an hour a day which I usually used on dungeon quests. Took 5 days to level 80-90 so I used it 6 times. I only did each dungeon once, so not a huge amount of XP saved. Might take you 7 or 8 quests for each of those to make it up.