Should I sell something to a friend that I got for free?
Are you having second thoughts about selling it?
I don't even want to sell it
It's your item now, so do what you want. If you want to keep it, that is fine, but if your friend needs it, you should consider selling it to them then.
I could use the money, but I don't want to give it up at a discount to them.
You might want to reconsider making that fast money off of your friend. It's not very considerate of your friendship to profit off of them when you got the item for free. Make sure this isn't going to harm your friendship.