Congratulations on your first finished project!
Good for you for sticking with it--for all five feet! You've done a great job on the scarf--it's very pretty, is a lovely colors, and has nice texture.
I think using cheap acrylic yarn for something that's going to face the elements is fine--especially when you're still just learning to knit. You're right: You can use more expensive yarn someday soon when you're more confident about your knitting skills. So as long as the acrylic keeps you warm (or serves your intended purpose) and is in colors you like, then that's a great idea!