I had trouble finding a ready reference to the ilvl ranges for Mists, so after hunting around all the usual sites came up with the following. I’ll revise this post if the numbers change.
Update 2012.10.03: Revised Heroic iLvl (was i440), JP iLvl (was i450), JP/VP rep requirements (no rep for JP gear, less for some VP gear), and added crafted weapons iLvl.
|Heroics||i435||i463/i476||i476 off final boss only|
|LFR||i463||i476/i483||T14 tokens i483|
|Raid (N)||i476||i489/i496||T14 tokens i496|
|Raid (H)||i489||i502/i509||T14 tokens i509|
So progression is pretty clear: Dungeons -> Heroics -> (LFR) -> Raid Normal -> etc. You can skip LFR by grinding out enough rep and VP to get into norlmal raiding.
Rep vendors sell i458 gear for JP (no rep required), and i489 for VP at Honored (neck/ring/cloak/bracers) and Revered. So planning your reputation priorities will be important.
Crafted epics are i476-i496. Crafted weapons are i463.