Aveiro Rossio Hostel is about a 15-minute walk from the railway station, which is located in a hundred-year-old building in Praca do Rossio street in the city centre. A night in the hostel costs 20 Euro which is not a very high price if you take into account that it is located next to the best bars and restaurants in the city. Nearby you can also find a fish market, which is opened every morning.
In the hostel I met some other Poles that I had seen (and overheard a bit) already on the train. As it turned out, they suspected me of being Polish and they were certain that we were all going in the same direction, even to the same hostel. Well, they were right and I had some new, friendly companions with whom I shared breakfast. I wasn't really surprised by all this situation. They had the same guidebook recommended by the Aveiro Rossio Hostel.
I recommend it too. It is one of the nicest hostels I have ever visited. It is run by a Portuguese family and adheres to the ecological rules of household management (e.g. electricity is generated by solar panels) and provides you with freshly baked bread every morning. What else could you want? Also, there is a terrace and free WiFi.
After breakfast and some packing I headed straight to Reserva Natural das Dunas de Sao Jacinto, because I had been informed that it would be closed on the following day.