Welcome from Ireland.
As others have suggested before me, try out as many as you can both in your price range and above. I say those above, because sometimes you can get a good deal on a used one higher up the range, when someone is upgrading. Providing you are happy with your dealer, then he will look after you and your machine. Sadly, here in Ireland, we are almost bereft of Bernina dealers, so, while I love my machine, I dread the day something goes wrong with it. It did once, the dealer put it in his store room and forgot it (he is well past retiring age). After several weeks, he told me he had sent it to the UK for repair. When I checked the UK, he hadn't. Eventually I got it back, but it took almost THREE MONTHS. Can you imagine how I felt?