How do you define an item is worth any amount of chaos? Basically, if it's not part of the game itself, then the API doesn't expose it. One of the things AIF might have done was create a custom property that calculated the estimated value of an item based on mods and stuff, not too sure but that's why there's no property to just value an item.
Max Implicit Value is something new, but consider the following scenario:
You want to loot 40 life leather belts
You want to loot 30 resist cold/fire/lit
You want to loot some 30%+ spell power wands.
In any of these cases, you'd have to use the more complicated and nearly impossible to use affix system of the plugin (which is why I said it cant handle the 5c thing easily) to match implicit affixes with the respective value.
The underlying question I asked before adding that property was, "but why"?
What if instead, you match metadata of the items you want, which is easy enough, dump BaseItemTypes, and instead just specified the implicit value you wanted to match, since there's only 1 visible implicit, and the actual stat on it doesnt matter because modified implicit items don't drop in the wild.
So, that's the idea behind the max implicit value, it was something new added for 3.0 because I needed it for testing some 3.0 stuff at the time, so that's why its not in the item filter guide:
https://www.thebuddyforum.com/threads/old-item-filter-editor-guide.157401/
To get current game data, you can go to the DumpTab and dump BaseItemTypes / Stats.