Further to the topic on dive luggage, I've just booked sports bag 'excess luggage' vouchers on Air Malta for an upcoming trip.
My booking is for diving equipment but you can book for other gear, such as golf clubs. There's a link to 'sports Baggage' on the Air Malta home page.
Booking online was fairly painless, though they wanted info such as passport number (so have all that to hand when booking). I had to complete the forms twice, for outbound and return flight.
The price is quoted as 15 euros per bag/flight but you can pay in other currencies (look for the choose currency buttons to the left of the online form). It was £11.34 in sterling, which represents a favourable exchange rate - I wish I could get the same for the whole holiday!