I mean considering he buys it for almost nothing he'll probably make a profit no matter what he sells it for.The idea is, just as you're out to make a profit, so is Tony.
He's going to make sure he has a loyal customer in you before he starts giving you deals. Although you can do whatever you want with the drugs you buy, they natural progression is supposed to imply that you use them to create/befriend addicts to setup your own drug den - if you're directly selling them, you're going to make a loss unless you're directly smuggling in the drugs yourself because, after all, you already bought the drugs from a dealer, who is offering that same price to everyone (except loyal customers of course). Why would people buy from you for more than they could buy from Tony? That's why selling drugs directly at the moment is supposed to be high-risk, low return; if you're selling on the turf of a bigwig, with his own drugs, you'll need to get a pretty good deal on them to turn a profit.
That is exactly how it should work ^_^
Buying drugs from Tony should only serve to make Tony trust you, and thus help establish your drug business. Reduced prices later on are merely to make it easier on people who want a lump sum of drugs quickly, rewarding them for consistently doing business with an old partner after going independent.
Sorry if this aspect wasn't made apparent. o_o; The current mechanic is just some polish I added to a very rudimentary system, but I plan to flesh it out at some point in the future.
Edit: Also, I should mention this in case people think I'm contradicting myself - The discounted prices are an easter egg for those who keep buying from Tony past when they could have gone independent. The progression I mentioned in this post is the direction the original game's code seemed to intend to steer players towards. While I tried to keep discounts as enticing as I reasonably could, I also tried to balance it with the original game's intentions in mind. When I talked about the discounts in previous posts, I was purely talking about the balance of the discounts, while this post is talking about the balance of the entire in-game drug economy. Just trying to prevent future confusion here! >_<
As for why they'd buy it from you instead of from Tony, well, why do you buy groceries from the super-market? I mean that's just how economy works intermediaries bumping up prices.
Maybe most random people don't feel comfortable walking into a drug-lord's mansion to purchase one hit of cocaine? Maybe Tony thinks it's easier to off-load 1000 hits of it on you for a fraction of the price, meaning he'd get a big influx of cash right now and he wouldn't have to deal with trying to off-load it on losers or having losers show up begging him for it when they're out of cash.
And yeah you don't really need any steering to realize that once you can bypass Tony and buy it directly from Colombia yourself that you wouldn't need to buy it from him anymore.
Going back to the 'why would people buy it more expensive from you than they'd buy it from Tony argument, why would you sell it cheaper than you bought it for, that's kinda unbecoming a drug-dealer, you're already wasting your time chasing buyers down, so why would you make a 50+% loss on the transaction as well?