PR is pretty much the only one that I think it probably doesn't make sense to buy (unless you really know what you want). Even at NEC, the price is $35 and the amount you get will almost certainly last you a lifetime. Using commercial cheese is very easy (just plonk some in -- you don't need much). And then as long as you keep a blue cheese going you pretty much have it for life (or you can culture it up on some rye bread and I *believe* it will store in the freezer OK -- haven't tried it). Really I suppose it depends on if you have something specific you want...