If the seller uses the Global Shipping Program you will be charged import fees at the time of purchase.
These are roughly equivalent to applicable duty (probably none on USED clubs) and sales taxes (GST/HST/PST) plus a ~$5 service charge.
If the seller ships directly by USPS/Canada Post, you will be charged the duty (again, if any) sales taxes plus a $9.95 service charge by Canada Post before the carrier will give you your purchase. (But golf clubs may be too large or heavy for postal shipment.)
If the seller ships directly by courier (UPS for example) you will be charged the duty (again, if any) sales taxes plus a $25+ service charge by UPS before the carrier will give you your purchase .
And here's the sneaky one.
If the seller ships directly by FedEx you will be charged the duty (again, if any) sales taxes plus a $25+ service charge which will arrive by mail after you have signed for your parcel and you have accepted your purchase . Your signature is an agreement to pay those fees.
All in all, this is one situation where you should either buy through the GSP or buy Canadian.