Airplane tickets purchase
Even though Paxos is too tiny to have an airport, it is easy to fly to nearby Corfu and catch a ferry connection from there (Corfu to Paxos by hydrofoil will take less than an hour). From April to September there are frequent flights from various European cities to Corfu or Athens. Check discount airlines such as Monarch, Ryanair and Easyjet as they have direct flights from several European cities to Corfu. Greek airlines, Aegean and Olympic air also have frequent flights from Athens to Corfu.
If you are visiting during winter, there are still flights from the bigger cities although not as frequent. If coming from further away than the continent, you would have to take a connection flight. Athens certainly deserves a lengthy layover.
Here are some websites helping you find the best air ticket deals: