$45 is typically the price for an 1/8, which means it is "one, eighth, of 28 grams", so it should weigh 3.5grams. Is that with or without the weight of the bag?

The bud alone, out of the bag, should weigh 3.5g's.

Another thing, it looks like it is already busted up. Avoid buying cannabis pre-ground up as it doesn't give you a good view of how good the quality is, the cannabis could be "Kiff'ed", that means someone could have shook off the trichs, making the cannabis less potent. They could also grind up other green, leafy materials, like spices, and add to it.

So yes, for $45, for 2.8g's, you got ripped off. For that price, judging by your flag you're in the States, you should have gotten at least some high mid quality bud, at 3.5g's.

Find a new dealer.