Well man, since your pretty new to the whole weed thing. Try to buy as much as you can at a time, the less you buy the more people will rip you off. Prices vary all over the country as well as with quality. Around my state, the lowest grade shit, schwag, it'll be hard, compressed, seedy, stemy, darker green, sometimes brownish color, a quarter ounce looks somewhat about the size of a half dollar. You can find this for $20-30 dollars a quarter ounce depending on how much of a dick the dealer is. Mid grade shit usually runs $20-35 for an eighth of an ounce. It'll usually be a lot fluffier, less seedy, less compressed, might see some red hairs on it. An eighth will look like a quarter or more of schwag. Usually pretty leafy from what I've experienced.
Then the highest level, dank, varies greatly. But pretty much what you get is uncompressed buds, bright green color, sometimes white, purple, orange, but usually very vivid colors, red hairs all over it, little crystals called trichromes that are filled with thc will be covering the really good shit. It'll have a very strong smell, a smell that is unmistakeably weed, but no two batches ever really smell the same. I've found that really good shit kinda has a piss like smell to it, very pungent. This stuff will cost you $50-75 an eighth depending mostly on quality.
Just my experience trying to help another fellow smoker get his legs. Try to get the dealer to weigh the bag infront of you, or get a scale of your own. You'd be surprised the shit some people will try to pull.