There are a handful of items that emulate (Ring of Evasion) and/or augment (Monk's Robe) class abilities. However, "class ability" isn't one of the effects on the estimating magic item prices table, nor have I been able to find other guidelines for pricing such abilities.
Are there published guidelines (preferably from Paizo/WotC) for pricing magic items that emulate/augment class abilities?
This is specifically for a PF1 campaign, but translating from 3.5 is usually straightforward enough that I'm tagging it, too. If there are contradictory guidelines for the two systems, the PF1 guidance wins out.
Best Answer
No, and there couldn’t be.
Class features make no attempt at consistent power levels. Just because a feature is gained at a higher level doesn’t necessarily make it more powerful. Every class is designed as a whole, and even then they’re not at all balanced (though they presumably meant them to be).
So it just comes down to comparing with existing items, crunching numbers trying to figure out how much the feature does, and gut instinct.