As others have said, weight restrictions depend on the carrier, but I saw several people have sent you links to RyanAir (Europe's version of ATA & Southwest Airlines). The best way to travel RyanAir is with a backpack. RyanAir is ONLY cheap, if you do not get caught up in all the add-on fees (baggage, check-in, meals, etc, etc). US passport holders will automatically have to pay 10,00 euros to check-in at the counter (online check-in is only for EU passport holders), but traveling with a backack is the way to go. No waiting for luggage and they do not weigh carry-ons, but travel light, and just wash clothes as you go. I recently took a family of 4 to Ireland for 40,08 euros for 4 days with 3 backpacks and an activity bag for the kids. We brought home lots of small gifts, that all fit in our backpacks. Also, buy food in the airport and take it on the plane. RyanAir sells food, but the airport is cheaper and security allows it over here in Europe, so why pay more.