For Aer Lingus:
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(30 euro each way, extra from Amsterdam (as you have to pay for it to be boxed and bagged). Book in advance as only six allowed per flight).
Ryanair:
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"Sporting equipment including but not limited to large fishing rods, golf clubs, bicycles, scooters, fencing equipment, surfboards, bodyboards, snowboards and skis and large musical instruments including but not limited to harps, double bass, guitars and drums are inherently unsuitable for carriage by airlines operating fast turnarounds such as Ryanair. However these items may be carried in the hold of the aircraft upon payment of an additional charge of £15.50/€22.50 per item, per one way flight via [broken link removed] or £20.50/€30 per item, per one way flight at the airport ticket desk or through a Ryanair call centre."
So also book in advance.