I don't think it's any more expensive than other hair types. In my experience, it's more about finding products with the right ingredients than about how much they cost.

I think that some people are just more into trying lots of products and designer products, and they would seek that out regardless of hair type to each her own!
My hair: 3b, corkicelli, medium porosity, medium texture, medium/thick density

Co-wash: DevaCurl NoPoo
Rinse-out: GVP Conditioning Balm
Leave-in: KCKT, Suave Naturals Coconut, or my rinse-out!
Gel: SS FHG (my new HG!!)... I also like HESMU, AIF, CJ CQ, BRHG, CJ PP and the occasional LALSG

Likes: Plopping!
Dislikes: Glycerin

CG and loving it!