It depends on where you live, the dealer, the actual weed, alot.

Generally prices are:

A dime = 10 $
A twenty Sack = 20 $

Usually depending on where you are either a dime or twnety is a G or so, sometimes two.

A 1/8 is about 25-30 $
A 1/4 is around 35-50
Half is around 70-100
Ounce is usually around 150-200$

Those are very generalized prices.