What decides which animal I buy

[Puella14]

So while looking through a price sheet, I saw that the price for an domestic animal varies depending on it's size. I knew that before and it makes sense but I started wondering how it the price gets determined, if I want to buy a animal. So if a village sells cows and they have all sizes from small to big, when I speak to a villager and want to buy a cow, I can only imagine two scenarios:
first:
One of the cows is just randomly chosen at this point and the villager just expects the fitting price for that one cow and it's size. Meaning if the price is too high for me, I can cancel and ask again and maybe a cheaper/smaller animal is choosen this time.
Second theory:
The villager expects the minimum price for the smallest/cheapest cow in town and I get bigger animals if I "overpay" this price, till it reaches the minimum for the next size.

Does anyone know how exactly this works or can do some good testing with this?  Maybe there is another scenario that didn't come to my mind? I don't really have a deep knowledge of how the trading works in this game but I could also try to do some testing, if nobody knows. I am really interested in knowing this   

[koteko]

My understanding is that there's a fixed "list", so if you try to buy a cow twice, the same cow will be offered. So if you want a bigger cow, you need to buy all smaller cows before - and you don't know the order in advance.

If I were you, I wouldn't waste too much time on this, though. In the next update we'll be able to buy "small dog", "big cow" etc, specifically.

[Puella14]

Oh really? Didn't hear about the "decide which to buy" plan so far. I only knew about the possible rework of skis, baby animals, spells reworked, bones and antlers and some more little stuff. That's really cool, thanks a lot for the info Hope this update comes out soon.

[PALU]

The next release out to be out "any day now", given that Sami's update in the beginning of August said he had intended to make a release before going on an August vacation for most of August, but didn't get it finished in time. I assume the reason it's not already out is that he decided to continue to fix bugs and add minor things to it for a while longer rather than rush it out (maybe as a result of thoughts during the vacation).
He's been active fixing bugs at the least (as can be seen by comments in the bug sub forum).

Edit:
Sami has posted a new development note, which is a much better indication of where things stand than my guesses above...

[caius]

Can someone provide a link to an accurate price list/comparison?  Thanks.