Juank

lately I've been buying weed through a friend, he picks some up for me when he buys for himself. Usually I like to cook it so i've been buying some brick weed for real cheap ($30 for a half oz). earlier though, i was thinking about buying some chronic, and this guy takes $30 for a teenth (1/16th oz). That's a little more than i want to spend, so i was going to see how much he'd sell an ounce of chronic for to see if i could get more for my money.
My friend called the dealer and he said that the dealer would only sell a quad (1/4th oz) for $130. I did some quick math, and that's $10 dollars more than if i just bought 4 teenths (which is the same amount). So the price went up for a larger quantity, and i said that it was bullshit. my friend then tells me that the second time you buy it he sells the quad for $120, which is the same price as if i bought 4 teenths (my last dealer gave discounts for buying large quantities).
I don't want to make accusations, but does it sound like my friend was trying to make money off of me, and the price being lowered the second time was his way of covering for himself? or is this a normal thing?