First off, that blanket is really lovely.
In regards to how much to charge? It depends on the garment and the materials. Say if you are making a sweater out of cascade 220. Generally speaking you would use like 1200 yrds. At lets just round up to 7 a skein that would be 42 dollars for the materials. But say it takes you a month to knit it. $126 isn't enough money for you time AND materials to make a decent profit. I would charge AT LEAST $175 for the sweater. See what I mean?
What I would do for you friend is charge her double the materials. Explain to her that you gave her a rather deep discount because she is your friend. Tell her that normally this blanket would be around $100 because of the yarn you bought and the time it took you. Really stress the time. The reason I say to explain this to her is because say if someone sees her out and asks her where did she get it. If she tells someone she bought it off of you because you made it for $60, then that person is going to expect that you do the same blanket for the same amount of time. And that is just shooting yourself in the foot. Also, I make it my personal mission to educate the masses about what really goes into knitting and the quality of the product. The thing is that we live in a society where you can go to target and get a "knitted" baby blanket for 30 bucks made out of acrylic and people think that is great!.
If you plan on doing this again, make sure you charge for your time and the materials appropriately. You knitting is worth it!