Honestly, I really don't care about the ap restore cost. I'm sitting at ap cap with nearly 150k ap in capsules that I collected from events and kitty boxes since spring 2015.
Enhancing is expensive, with terrible chances of success. This low reward to effort ratio makes people quit; which has not been addressed at all. I'd much rather have something that gives you +1 enhance at a cost of 50k ap and making the item perma bound.