I could spend a MONTH in this place. It is absolutely extraordinary.
As for admission, adults are 19.95$, but bring your student ID and get in for only 11.95$. Or show your AAA card for 10% entire purchase. Anywho, price is SO worth it. There's something for everyone there. I brought my family a few months ago. Mom liked the gemstone room, brother liked a the dinos (ah-MAZING) and Dad liked the exhibit art.
I personally like it all. I think everyone in Pittsburgh should re explore Carnegie Museum at least once a year.
What an amazing museum. If you're visiting Pittsburgh, its literally a must see.
I suggest going in the AM on weekdays, to avoid large weekend crowds.