The price of imported miniatures is heavily dependent on the Foreign Exchange (Forex) markets. Specifically the strength of Sterling compared to the Euro.
Just before and immediately after the UK's decision to leave the EU the Forex markets were absolutely potty with rates fluctuating widely. We didn't know if we were going to be able to reduce our prices or if we'd have to put them up. It changed daily.
At the moment it looks like, when the dust settles, Sterling will be somewhat weaker and we'll have to increase prices. But like all such predictions it's an informed guess at best.
The Forex markets should settle down over the next three or four weeks; they always have before. Only when this has happened will we know what to do. In the meantime prices will remain at their pre-referendum levels.