Not many of the TDs carry rep pens which is a pity. It would've been great if some of them do carry some pens, or at least the "popular" ones.
Having said that, currently I'm taking a risk on
gavelock.co that seems fairly legit despite having no testimonial from anyone whatsoever. (I think I'm blinded by the cheap prices compared to other rep pens sale providers)
We will see if the usd29 meisterstuck 164 rollerball actually arrives. Will update in a month!
Edit: added website of non-trusted dealer, gavelock