Gazelle? Does anyone know anything about them?

Probably everywhere except in Dieren.
Just walk into a shop a bike shop that sells roadbikes (racing bike specialist). Every dealer may have one or more.
But perhaps the chance is bigger (and price lower) when you buy it from private people.
The auction site Marktplaats.nl has almost a monopoly in NL.

Just check out http://kopen.marktplaats.nl/fietsen-en-brommers/fietsen-racefietsen/c464.html
and try to make appointments with the sellers in the areas you're going to visit.

When you are in the area of Dieren, you have a good chance at larger dealers like De Pedaleur (Doetinchem) and Goossens (Borculo).
In the past there were authorized Gazelle Race Dealer, who had exclusive rights to sell Gazelle Champion Mondial, but Gazelle is almost dismantled when it comes to race bikes. So, the actual Gazelle dealer network doesn't make any sense.

No chance that you can buy something from Gazelle directly.
Even a company tour doesn't make a lot of sense, I think.

Yeah I have been checking out Marktplaats. I did indeed not expect to find anything in Dieren. I will try to get my dad to drive me to Doetinchem and check that store out. In the meantime I will keep stalking Marktplaats.

Thanks man!