Magic Plants cost question

[Thor Odenson]

I see that the formula is
Price = spell level × caster level × 2,000 × yield per day × growing season multiplier.
But I applied this to the Goodberry Bush and it comes out vastly different.
Goodberry 1st x Caster level 1 x 2,000, x 6 berries x year round 4 season = 48,000 gp. The Bush is only 8,000 though.
The Tree of Knowledge is Augury 2 x CL 3 x 2,000 x 2 apples x spring 1 = 24,000 maybe 12,000 since it is 1 apple of the 2 colors. But its price is 3,000.

Did they just not follow their rules? Am I missing something from their rules?

[Quixote]

They didn't follow their own rules. That's a pretty common occurrence with magic items and such.

Goodberry and Augury are great examples of highly situational spells that just aren't worth as much in 90% of situations as other spells of similar level.

Healing up to 8hp in a day and saving 5sp on trail rations? Learning that a given action will (maybe) yield good or bad results, or both? Just not something you need on demand.

[deuxhero]

Magic plants largely exist as dungeon features to include water walking/portals/ect. in more "natural" dungeons (and provide a bit of healing that can't be sold at profit or stockpiled in case of goodberry bush). The gold is largely arbitrary since even with Harvest Season to remove the growth time, they're not really useful to PCs.

[Meirril]

As with all magic items, a fair judge alters the value to match the usefulness of the item. In this case, low value spells were adjusted to be below the formula cost. If you found a spell that has higher utility than the formula would indicate the price should be adjusted higher as well.

The formula are guidelines, and making adjustments is part of a GMs job.

[blahpers]

The goodberry spell normally produces 2d4 berries per day (expected value: 7), so the yield per day of a goodberry bush is closer to 6/7 (six sevenths), making it slightly overpriced, not underpriced.

Edit:

The tree of knowledge doesn't produce an augury per day. It produces an augury per week and a +5 to a Knowledge check boost per day. Its yield per day for the augury portion would be 1/7 (one seventh), making the tree's augury portion worth less than 1,000 gp. Presumably the Knowledge check boost makes up the rest of the price, approximately that of a hypothetical once-per-day 1st-level spell.

TL;DR: They stuck pretty close to the formulae on these plants.

Edit the second:

The tree also should have 325 gp worth of material components 25 gp worth of focus component for augury built-in. That's still in the "wiggle-room" area, though.