Please Help!!!!!! My Girlfriend Is Over Demanding

My girlfriend is never satisfied with me. She wants more of everything. If I give her money, she wants more. If I take her shopping, she would exhaust my money without having compassion on me.

I just started working and I earn little. Recently, I gave her 40k for a blackberry phone; I don’t even use a blackberry! Last night, I got a message from her demanding 100k for a Brazilian hair and a shoe she wants to wear to my cousin’s wedding next week. I am tired of her over-demands. Sometimes, she threatens to leave me if I don’t respond to her needs. What should I do?