We have an egg poacher, which is a good few years old. Probably a number of decades old, in fact:

Our trusty egg poacher
You add water below the four “cups”, grease each cup with a little olive oil before adding an egg and let it boil with the lid on until the eggs are
poached. Simple. (The preceding link to Wikipedia shows how real poached eggs should be cooked – too difficult for me first thing on a Sunday morning!) Except that over the years eggs seem to have got bigger. Our local supermarket often only has large sized bio-eggs, and these overflow out of the cups when you crack them. Which makes a horrible mess.
So a couple of weeks ago I bought some microwave egg poaching containers on E-Bay:

The microwave egg poachers (well, two of a set of four)
I have experimented with microwaving the eggs in them at different powers and for different times, but have come to the conclusion that you can’t avoid cooking the yolks before the whites are cooked. Which is fine if you like hard-boiled eggs. But we prefer our eggs runny in the middle.
So for now, it is back to the drawing board. Ruth found something which looks like it might work, at amazon.de. But the price didn’t work for me – 50 Euro for four bits of plastic is too much. However a quick check at amazon.co.uk showed that they were only five pounds for two there (plus postage, but even so the bill is less than 26 EUR for 4, which is still not cheap but a darned sight cheaper than from the German store! Right now, I am waiting for them to arrive.
Have exactly the same problem – have never yet managed the perfect poached egg in the microwave poachers, so have just followed your advice and ordered the silicone ones!!