Honestly the only way to tell for sure you probably got ripped off (without pictures, more info., etc.) is if the 30 grams was loaded with seeds and stems. Other than that if it gets you high, smells good, tastes decent, looks decent but has 3 seeds. It can't be too bad of a deal I would think. It depends a lot on location too.

Don't sweat it, you'll get used to it quick and you'll probably get ripped off a few times in your career heh. I was ripped off only $20 last weekend. It sucked being ripped off but I got friends who hooked me up and gave me my money back although it wasn't even their fault so I came out ahead.

Anyway yeah keep smoking and keep talking on sites like this. You'll learn.