Rental rates vary according to the owner but you can expect to pay between €200-400 Euros per week for a 2 bed apartment in Paphos depending on the season and size of apartment.
The best prices can usually be obtained by renting direct from the owner. You can see a good selection of privately owner properties here on this Paphos apartments page. For long term rents, expect to pay between €300-400 per month for the same apartment.
Remember to negotiate for long term rentals as some property owners, especially Cypriot owners, get greedy and ask for crazy rentals based on multiplying their weekly rate by however many weeks you want to rent. It's a buyer/renter's market given the large number of empty properties in all towns so if they want your business, don't be afraid to haggle!