as the title states, i have 2x mystical aeridini essence, looking for at least 750dia/equivalent gold for each one
proof:

Hey do you still have them?

yes, yes i do

I think that's probably cause no one's gonna pay 750 diamonds or 750k-1.5m gold (depending on what conversion rate you're going for) when they could buy the exact species they want enhanced for the diamonds, and mysticals are currently on the broker for 700k and 1m (though, the 1m could be good news for you, again depending on what conversion rate you're going for). Most people just don't have a use for slightly better colors and restricted trait possibility, and I'm included in that.
(I mean all of that in the nicest way. Pricing stuff on here is hard, and I may even be wrong. I'm just guessing and estimating.)

That being said, I am desperately in the market for any Aeri essences I can get my hands on. So I've got an offer for you: 200k gold + up to 3 eggs from any pair in my stables.
Feel free to counter, I'd love to barter with you! I also do have 200 diamonds per se, but they're the first 200 I've ever gotten my hands on, and they were just 220k in the currency exchange. So if diamonds will be included, it'll be at a 1 to 1,100 rate.

selling yourself short with your ratio. 200 dias can sell for 1800-2k per :)

Haha thanks, but the ratios are much lower in the buying gold side of the currency exchange ^^ I've been watching it closely, in buying diamonds it tends to be 1:1800-1900, but buying gold is 1:1000-1100.

yeah it is xD the going rate for dias v gold is generally 2k:1 though. I actually got my gold pile started buying and selling dias xD they sell so quickly