We will be spending one night only in Cagliari and are looking for good budget accommodation? We are travelling mid-September and we plan on seeing the Old Walled City and eating on the Marina. Any suggestions?
We don't research Sardinia so we don't have any lodging recommendations. You may want to check other guidebooks that try to cover everywhere with general information. I recommend the Lonely Planet guidebooks. You can also try sites like AirBNB or other hotel booking websites.
We stayed at the hotel Due Colonne which is smack in the middle of everything for 100E in June. You can check them out on TripAdvisor. The staff was super helpful.