After being exposed to some excellent fountain pen propaganda from Hacker Public Radio;
I got inspired and went ahead and bought a cheap PierCarlo d' Alessio from a guy on the Swedish eBay Tradera.
It uses small standard international ink cartridges and, according to the seller, there isn't enough room in it to fit one of those convenient converters. I'm unsure of the size and shape of the nib. However, I have come to love it, even though my handwriting skills still sucks big time, I find it a lot of fun to write with a nice pen in a good notebook. I try my best to establish a routine to write a little with it everyday and I hope my skills (or currently lack thereof) will improve over time.
A note to self: If I were to buy a new fountain pen sometime in the future I would probably go for one with an even finer nib.
Update 2021: This was actually a really nice fountain pen. I either lost it or it broke down somehow but I miss it.