If I have this right, a bred pet's base stats will be somewhere between the base stats of its parents. Does mana work the same way? For example, say I breed a regular generated pet with 90 mana to an enhanced generated pet with 100 mana. Can the offspring be anywhere in the 90-100 mana range?

I'm planning a max-stat project, and I'd like to end up with max mana without using any more diamonds than necessary. If the first generation can be regular x enhanced, with a 1/11 chance of babies having enhanced-level mana, the extra time it will take to get them is more than worth the chunk of change it will save me.

As I understand it, yes, you're right for the first part.

The mana seems to be based both on type of essence (regular vs enhanced/mystical) and type of pet (fabled vs regular).

For example, all at level 0:

For nonfabled, or regular, pets:
Regular generated zolnixi has 90 mana.
Regular generated aurleon has 90 mana.
Enhanced generated aurleon has 100 mana.
Enhanced generated zolnixi has 100 mana.

For fabled pets:
Regular generated aeridini has 110 mana.
Regular generated ny'vene has 110 mana.
Enhanced generated ny'vene has 120 mana.
Enhanced generated aeridini has 120 mana.

(Mystical has same stats as enhanced anyhow, saves you the money)

So to end up with max mana guaranteed, its better to have all enhanced parents.
With regular mixed in, you'll end up having uneven mana in your offspring. The lowest mana offspring might make it difficult to maintain the highest amount of mana possible, but if its a chance you're willing to take, or if you intend to keep breeding until you have generations with the highest mana possible, it's a viable option, just may take more time.

Thanks so much! My plan is to have regular x enhanced pairings for the first generation, and only keep the offspring that have enhanced-level mana. I understand waiting for that will add 2-3 months to the project, but I'm fine with that if it will save me the 1500 diamonds that two more enhanced parents would cost! :)

If anything, I suggest looking into breeding with pets set for breeding on the Advanced Search. It's more affordable if you happen to find pets with traits you want (or anything recessive to the traits you want), then just dye the offspring you breed from the parents. ^^

I often suggest players who wanna start breeding projects but don't have the essences to look for pets that are up for breeding, or PM the owners (if they've been online recently) if a deal can be made. While it takes a little more time, it may save money. I know dyes may be expensive (100k per dye it seems), but it's worth it in the long run (if an enhanced essence is bought, that's 750 diamonds, and at 2500g each, that's 1,875,000 gold, which can buy lots of dyes).

I can give you more tips via PM if you'd like. :)
edit: I'm a bit of a penny pincher myself, so I thought I could help in this line of thinking. ;w;

omg cool thanks, this is actually legit useful for me

And also, if you are thinking of doing a non-fabled pet max-stat project, you might want to keep an eye out for 4-star pets, since those will have 120 mana, which is higher than the enhanced essences.