The only ways of getting to the islands are by ferry and plane. There is a very small airport on the islands and I think the prices are relatively reasonable. Most people get there by ferry, however. You can take one from Rossaveal or from Doolin. The one from Doolin, ran by Doolin Ferrys, is faster but costs more money. The one from Rossaveal takes a lot longer to Inishere, but to me is more scenic. You can board a bus at the Aran Island Tourist Information building in Galway which will take you to Rossaveal where you get on the ferry. I remember the fare being about $15.
Flights by Aer Araan wil normally cost around 44 euro, although there are a number of offers available, sometimes combined with B & B arrangements.
The flight is somewhat brief, but the service (roughly hourly) provides for some magnificent views.
These little planes then 'hop' onto the other two islands. One of these hops is (according to a bloke I met in a pub in Kilronan) the second shortest scheduled air route in the world.
When it comes to transport around this Island you have five distinct options in order to complete the ‘ring’ of the main sites which includes Dun Aengus, the seven Churches, the man of Arran house and the seal colony.
1) Walk – go on it will do you good
2) Bicycle, take one on the ferry for a few Euro Extra or rent one from a couple of places in Kilronan at 10 Euro a day
3) Use the public bus – only to Dun Aengus, at 3 euro each way. Infrequent.
4) Use one of the hoards of Minibuses that depart from the pier. They do the circuit at 10 Euro per head
5) On a pony trap. The same route and by negotiation. Usually this works out to about 20 euro per head.