Haven't sold a snowboard but I have sold the odd item which has been fairly bulky and heavy via ebay.
Firstly, do you have suitable packaging material such as bubble wrap. cardboard box etc ?
If so, partly wrap/box item and weigh to find out total weight.
Then find out if there is a myhermes or collect plus drop shop fairly near you or if they collect from your local area. Check their websites and set up an account - it costs nothing to set up an account.
The websites will show you how much courier delivery will be with/without signature but tracked all the way is best for an expensive item.
myhermes were a bit crap in the run up to Christmas but they haven't lost anything I've sent yet (200+ parcels in 6 months).
List item with the option of the courier (factoring in the charge plus packing materials you need to buy if you don't have already have enough stuff you can re-use) or local pick-up if your happy to have someone collect it (absolutely must be cash payment on collection though if you are allowing local pick-up).
Take plenty of photos including the travel bag and be honest about any imperfections/ wear and tear to minimise the risk of an "item not as described" claim by purchaser. Do close up photos of any such defects/flaws.
I'd recommend using a starting price of the minimum amount you'll be prepared to accept for it if you have one in mind.
Good Luck