The Black series is supposedly positioned as the top of the line for Odyssey. The pricing therefore is like that for Lexus in Borneo Motor (you can almost relate white hot and white ice to Toyota). They "justified" the price with "better" material (e.g. tungsten weight) and better finish. Ultimately, I would say it is personal.
Similary for the white hot tour, the material and finish (bronze finish) is slightly diff from the standard odyssey white hot xg. This series was supposedly on tour use, until the black series was introduced to the tour.
The white ice is the new boy on the block, boosting of a new firmer insert (the inserts for the other three felt the same). But the newest feature is the interchangeable weights (only for some models). Hence, the price is higher for those.
The different models differ in the terms of the head shape, balance and sometimes, weight (e.g. #1 and #2 are blades, #9 is heel shaft). The 2-ball is a series by itself among the product, and there are different models within too (eg. blade, CS and V-line).
These model are quite standardized among the four series. Btw, there is a also a Odyssey divine series, among others. Go see their website.
Price diff among models? For the new white ice, the price diff is in the interchangeable weights (some models do not have it - think the V-line and blades). Hence, they are lower in price. Otherwise, the price diff is mainly due to demand. Blades and the 2-balls are generally more popular, hence, may be priced slightly higher.
Note: This is just my personal observation. May not be 100% correct. I also not employee for odyssey.
Bottomline, find one that you are comfortable, both in terms of feel, look and price.