Can anyone recommend a decent fountain pen that’s easily available and affordable (USD 100 - 200)? All I usually see are vintage pens that are only available through specialist dealers. Surely somebody today must be making a pen that’s good enough?

You could try things out with a Platinum Preppy for about 5 USD. Past that, a Pilot Metropolitan, or a Lamy Safari would be good entry level pens, in the 20 USD range. For 100-200 USD, you can get a very nice pen like the Pilot Custom Heritage 912, or a Pelikan M200. I'd recommend trying out the cheaper options first so you get an idea of what sorts of nibs you like.

http://gouletpens.com

http://jetpens.com

http://nibs.com

Are decent places to start looking for more modern pens. Hope that helps.

I'm quite fond of Franklin-Christoph, myself: http://franklin-christoph.com

Also, the Pilot Stargazer is an excellent pen in my opinion in that range: https://www.jetpens.com/Pilot-Stargazer-Fountain-Pen-Black-1...

You price range has a wide selection, depending on what you want. Feel free to reach out if you want to chat about pens; I've been "into" them for about four years now. I use my real name here and pretty much everywhere else, so I shouldn't be hard to find :)

Try the Pilot Vanishing Point. It writes well and it is the only major market retractable fountain pen.