Hi, Elzbieta. Welcome! Does your mother have a harp already? If not, your best bet would be to find a teacher first, who can probably hook you up with a rental harp till you have a better idea of what you like. There are a lot of harpists in NYC, so you should be able to find someone quite easily. Here’s a link to the Harp Society teachers’ directory, but there are many more people than have listings here:
http://www.harpsociety.org/Resources/TeachersDirectory.asp
You could also contact any of the big schools/conservatories, the union, etc. to find someone.
EDIT A pedal harp is a substantial investment, not something you’d buy on a whim. You want to be sure you like playing the harp and find a harp you absolutely love before shelling out that kind of money.