XP+GP Cost Vs. Feat Cost for Wild Cohort-like minion

[Coidzor]

So I was thinking about homunculi & minions & such, and realized that there's no real way to ritually bond one's self to an animal, with the closest things being animal companions which are easily dismissed & quite ephemeral due to their nature as disposable meatshields & wild cohorts which are basically animal companion lite.

Which lead me to wonder about the balance issues inherent in shifting something like wild cohort away from having the feat cost to having an animal that is advanced in exchange for money & experience in a way similar to how an artificer or crafter could increase the HD and abilities of his or her homunculi with either a hard cap on animal advancement based upon character level/ECL or an effective cap based upon the cost to advance the animal.

What do you think of this idea? Any immediately obvious problems or issues that would have to be dealt with (beyond deciding upon a cost)?

On a related note, is anyone here familiar with the efforts of anyone who has gone through & determined why the animal companion options are deemed appropriate to the level they open up at or even gone through & given their own spin on what animal companions are appropriate to open up at the various given levels of play?

[Godskook]

What's wrong with Handle Animal for most purposes? Sure, no share spells, but that's kinda powerful for a non-class feature.

[Coidzor]

What's wrong with Handle Animal for most purposes? Sure, no share spells, but that's kinda powerful for a non-class feature.

Because then you have to add warbeast for scalability and that only stretches them another level or two of play, if that, before one would just want to replace them with the next animal... which mostly can only be acquired either by being a class with wild empathy or some way of diplomancing animals/magical beasts or by purchasing warbeasts/magebred warbeasts.

Doesn't really organically scale and mostly just seems... choppy with having to cycle out animals as they either die or are retired so that one goes from having dogs to having leopards to having bears to having dire tigers rather than, say, having a pack of dogs that one bonds with to the point where they get stronger as one invests in them and become more and more like, say, the platonic ideal of Dog. Handle Animal also only lets you get whatever animals you can buy in the campaign world(which means mostly warbeast by volume) or requires one to have wild empathy to tame wild animals without re-writing the Handle Animal rules.

Whereas the idea here is having an animal that one has bonded with that one just scales up with HD and other improvements at a defined rate that costs the character however much the character wants to spend on the animal or animals rather than taking up a feat slot.

edit: Is that more clear?