I'm personally treating stimpacks like potions of cure light wounds. I think they'll be cheaper though. Super stimpacks will be moderate, but for everyone you use in a 24 hour period, you'll have to make a fortitude save that increases with each super stimpack use or lose con (to simulate possible "overdose" that happens in Fallout 2)
I posted last, but I am waiting on Chase to at least say or do something before Alicia can post again. I think Felix and WD have been busy RL since I haven't seen them on-line elsewhere these past few days either.