Call of the Hero spell cost
 

I'm approaching 55 now and have been checking prices on this spell for a while. Seems to be consistently 20k compared to everything else < 1k. Is it really that rare of a spell or is it just because its so important? Also are there any good spots outside of Sebilis to pick up 55+ spells?

it's pretty rare and the utility is the best. if you're not in a guild it's pretty pricey.

you can farm ancient wyverns in SF or that cliff golem in OT that can potentially drop it too.

I think it can also drop off the named cycle in SF, although rarely. I may be mistaken