I would be very stupid to release an animal to the wild, getting only 20 leafs, if I could sell it for 500 (or even more)!.
And that’s exactly why Frontier does usually not sell top animals. If they would, they would either have to adjust to the average market price, asking hugely inflated prices, and thereby hurting new players, or, by keeping their current price strategy, to drastically undercut the market price and thereby hurting selling players and maybe even discourage some from selling at all. And you said yourself, you sell your animals for more than their default price. Why would you expect cheap Frontier animals to always be of high quality? And since this poor monkey seems to be the only one left of Frontier’s animals, you can be sure that the other monkeys had decent to good stats and just sold really fast.
But I have never had major problems finding Frontier animals with 50-67% ratings throughout or even better with maybe one low stat, usually size or immunity. And on and off even a gold animal. It just might take some time.
The increased storage is helpful since you can keep an eye out for better Frontier animals long before you’re actually ready to populate your habitat. Particularly if you can tell that certain species or females are harder to find.
If we all (and again, I include myself there) would sell most of our high quality animals for a reasonable price (i.e. not much higher than the suggested price), we wouldn’t have to rely on Frontier’s animals. But since there are so few animals available for a lot of species, this allows mediocre animals to be sold for thousands of CC. And people don’t bother to sell for fair prices since they have plenty of CC and it’s too much trouble selling them all individually on the market. That is the core problem, in my opinion, not the cheap and often lower quality animals offered by Frontier.
We are lucky that Frontier decided to put more animals on the market. In the past, there often was not a single animal available for some species or maybe one or two zero fertility ones for 10k CC.
ETA: Check how many minutes are left before a new batch of Frontier animals willbe loaded. This gives you better chances to find good deals before they’re snatched up.