My spending varies, but I mainly only buy my Wen products on QVC and when they have specials or sets. So I may buy a huge lot one month that will last me anywhere from 2-6 months and nothing in between. Like I said, it all varies.
I too have Asian hair, but my hair can be bi-polar at times. I grew up having really straight hair, but as I grew older my hair started having waves. So some parts are still straight and others wavy. I love Wen because it'll tame my waves and make my hair look nice PLUS I don't have the need to wash everyday or even every other day. I recommend trying something other than Fig (unless you really like it) since it can be heavy and you mentioned you have an oily scalp. Maybe try Tea Tree? Some describe the smell as medicinal, but the smell doesn't bother me at all. It'll normalize the oiliness without it being drying, at least that's what I've come to find. Also like someone else recommended, maybe try more pumps? I too have long hair (in between shoulders and middle of the back) and I use 10 for the first and 10 for the second. In case you wanted to know I'll switch it up between Tea Tree, Bamboo Green Tea, 613 or a seasonal (current faves are Summer Mango Coconut, Summer Honey Peach, Spring Orange Blossom). Hope this helps!