Perhaps three isn't too many, but it does feel unwieldy. Nevertheless, it seems to me these are all different distinctions in value, even though many people write as if they are the same:
Whether something has extrinsic or intrinsic value is a question of where it gets its value—i.e. from something else or from itself. (Instrumental value is thus one kind of extrinsic value, but it is not the only kind; Rae Langton, in her 2007 Phil Review paper, “Objective and Unconditioned Value,” proposes symbolic value as an example of noninstrumental extrinsic value.) This is “something else” intensionally, and not necessarily extensionally, so constitutive value is a form of intrinsic value. E.g. if Mill is right that virtue is valuable because it is a part of happiness, which has intrinsic value, then virtue has intrinsic value.
Whether something has conditional or unconditional value is a question of whether it has its value in virtue of its relation to something else, or rather in all circumstances. Constitutive value is thus an example of intrinsic but conditional value. (And Langton gives the additional example of self-conferred value.)
Whether something has priceable or priceless value is a question of whether there is anything for which one could rationally trade it. I suppose if something has extrinsic value then it must be priceable—it would always be rational to trade it for either the thing from which it gets its value. But consequentialism embodies the notion that intrinsic value can also be priceable.
The issue I’m trying to work out is the relation between un/conditionality and priceability. I think there’s such a thing as conditional priceless value. Consider, for example, the value of time spent with a loved one—it might be priceless, but only on the condition that the relationship hasn’t fallen apart. Is there unconditional priceable value? It strikes me that there could be, but you could rationally trade a thing of unconditional priceable value only for another thing of unconditional value (either priceless or of equal or higher price).
I care about this, obviously, because the Kantian idea that humanity or rational nature is an end-in-itself usually contains all of these: intrinsic, unconditional, priceless value. And I suspect different kinds of value are carrying more weight than others, in different arguments. More specifically, I suspect the really crucial Kantian insight is that something or things have value without price. And, yes, I'm ignoring the subjective-objective distinction, for now.
What do you think?