I'm a different expert, and we answer questions like yours all the time. You have met yourself a romance scammer.
Do not send her the money for the tickets. She will not be on the plane. The only way to see protect yourself when buying tickets for a stranger is to order in her name and bill it to your credit card. You can do that from anywhere in the world and get buyer protection that way. She can get the eTicket and with a valid passport that matches the identity and the passport number of the traveler, she can get on the plane.
Of course, that's why she wants you to send the money to her instead. She is not who or what she says she is and she doesn't really have identification in her phony name. She's a group of thieves hiding behind the photo and profile of a beautiful woman, and they are looking to swindle you.
I know that you won't want to believe me. I am sure you'd rather believe her. But I can tell you that THERE IS NO SUCH THING AS A DECLARATION FEE NEEDED TO LEAVE GHANA. The Declaration Fee is a fiction that is only found in internet romance scams.
The Ghana Immigration Service specifically warns people not to send money to people who profess to have to pay a fee to leave Ghana. You can see that right on its website. If Ghana Immigration says there is no such fee, she has asked you for the one thing that proves she's a fraud.
To see this for yourself got to the Ghana Immigration SErvice's website, and choose the FAQ link from the column on the far left of the home page. You'll see the warning about BTA's and Declaration Fees. All anyone from Ghana needs to visit you is her visa, her passport and her plane tickets.
Again, do not send her any money. You will never see it again. Cease all contact with her and report the fraud to your authorities. Do not EVER send an internet romance money for plane fare. ALWAYS buy it with your credit card under her name. If your online love objects, there's only one reason for that -- she wants your money and not the tickets or you.
If you have photos or information about here you want to upload with your reply I may be able to tell you more, but it won't change my mind. She has asked you for the one thing that even her country's immigration service says does not exist.