Cleric: Bang for the buck gear?

[Ruien]

This looks good. You're asking the right questions and already have enough mana as-is to participate in a CH chain; remember, the baseline standard for comparison will be the gear worn by guild cleric bots, and they may only have around 3200 mana at level 60.

A couple of cheap mana upgrades to consider:
-- Breastplate of Forbidden Rites
-- Greaves of Forbidden Rites
-- Crystal_Spider_Eyes
-- Supple Scale Armband

It's also worth rolling for scout until you get Talisman of Benevolence (or eventually just buy Nevederia's Right Eye instead).

Note that the Skyshrine armor is a bit better than Thurg armor, but it's also much more expensive. The Thurg armor MQs are the best value for the price.

Finally, all of the comments about going CHA are good advice especially for duoing, but I keep a separate CHA set to swap out for this purpose. For the purpose of a CH chain, you want maximum mana, just as you surmised.