I never buy weed by the gram. It's just too small of an amount for me. I have a great connection (one of my good friends), so the prices for some very good quality high mids are:
$10 for 3.5 grams (eighth)
$20 for 7 grams
$40 for a half ounce
$80 for an ounce
If I want some really dank shit, I usually buy it for between $30 to $60 for an eighth. However, if I pay this much, it better be some very kind bud.

The best thing to look for regarding price is to have a good hookup, such as a friend.