Cleric 19/Dread Necromancer 1 have two pools of Turn Undead to feed each Extra Turning Feat. There's a start.
Cleric usually. Archivists don't get turn undead, DMM only works on Divine Spells so Dread Necromancer won't like it.
Chameleon only gain a few spells and I'm not too sure they can do that really...
Incantatrix also can do crazy-batshit shenanigans with Persistent.
Beside from dipping 1 level in something that grants Turning, there is a variant druid from a dragon magazine called Wild Reaper or somesuch, which gets turn undead at lvl 12. Can't recall the number though.
Now for the rest of the CO crowd to prove how easily one can do much better than this