The only thing that is directly answered by the rules is the cost.
PHB pg 112:
Wealth Other than Coins:
Trade Goods Table
1 lb of Tobacco costs 5 sp.
As far as effects, they don't directly exist for tobacco. You have already disregarded the main source (BoVD), and I would agree for 2 reasons.
- Most civilizations don't make tobacco illegal
- I've never smoked tobacco that potent that a saving throw would have been required to avoid negative effects.
However, if you want some mechanical impact and not just flavor, you could look at some of the weaker alcohols present in the game to see what kind of FDC you'd need to avoid "addiction". Again, tobacco addiction isn't the worst so even if you are forced 2 days without the worst thing to happen is you'll probably be a bit snippy with people (-1 or -2 on diplomacy cks?)
I like the feel you're going for for this character but I'd probably just stick to knowing the price and maybe going with what @Cow of Doom said as far as giving people a chance to notice hiding based on smell. (not guaranteed, but if they fail spot/listen maybe they can have a "Scent" check (Wis roll +1-+5 modifier depending on strength of tobacco smoked and last time it was smoked.) BTW, pipe tobacco does have a MUCH stronger scent than regular rolled tobacco.
Sidenote: possible "flavor" text, wiz/sor casting prestidigitation could alter the flavor of tobacco making it have a unique flavor!..the possibilities are endless, but it would definately increases the cost of tobacco if purchased that way. However, your party member could always burn a 0-lvl spell at the end of the day for you! (Side benefit for party members, it makes a nice aroma which is way more appealing that burning regular tobacco!)