Is this a good price to sell?

I was borrowing a headset for my 360 from my friend. Then when i got a new 360 I just put my old one away. Then my friend came up to me and he said he wanted to buy my old hard drive. Keep in mind its a 20 GB. I said 30 dollars. But i wanted to also buy the headset from him i was borrowing. He said he would sell that to me for 15 dollars. In total that leaves me selling him the hard drive to him for 15 dollars. Is this a good price to sell it at?