Where could i buy a windsurfing board bag?
You can visit the site easy-surfshop which has a lot of surfing equipment. You can find a great solution for the bag.
You can also check out local ad sites or groups on Reddit or Facebook where people sell their equipment boards, surf bags
Drift Board Bags are the guys you need – they will make you a custom size: http://www.driftboardbags.co.uk PS Maybe time for a new modern big board – not only will it be shorter but also a lot lighter, faster etc etc ….!!