Ball point pens are the standard. You see them everywhere. They are cheap, really don't take any skill to use, and are disposable which is just what most Americans like. But a few months ago when I learned about fountain pens, I decide to give them a try.
It turns out that they are actually quite popular among writers and calligraphers. They provide a unique feel when writing that's unlike any ballpoint pen I've used, requiring very little pressure. They are also very cheap to refill and the fact that you can buy cartages that you can put whatever ink you want in them is pretty interesting. They are usually more expensive to buy initially than a ballpoint and require a little getting used to but I have found them to be very enjoyable to use.
I'm currently using the very popular "Platinum Preppy" that is available for around $5. I own four that I have scattered around the house and one at the office. I currently have almost 20 refills which can be purchase for about $0.50/refill. I might upgrade to a Lamy Safari soon but right now I'm happy with the Platinum Preppy and it's nice having several that are all the same.