Way to get the base cost charge for instance of WBS

I need to calculate the shipping cost of a very specific cart scenario, and in order to avoid re-defining the unit base price, I’d like to retrieve and re-use it from a specific WBS rule. I’ve searched in the code (and in the DB) and I have a pretty solid knowledge of where all that info is stored. But is there any public method to get whole tree unserialized and then guide myself down to the data I need, or should I write my own method to read the option, and then find my way through? https://prnt.sc/nhjdGUR-ajMu In the previous image, I’d like the price marked by the arrow (supposing the rule’s key is 3)