I think nordiver may be a bit off on the taxes.
Here's how it is:
Norwegian VAT is 25 %. That's the only tax on spearfishing or sports equipment when you import something to Norway.
However, the tax is calculated on the basis of the value of the item (excluding any national taxes in the country of origin, IF the shop will deduct them) and the shipping cost. So, if you buy a $60 trigger mech from Neptonic and it costs $20 to ship, that's $80 total value. The corresponding VAT is $20, giving you a total of $100. Additionally, there's the commission which is charged by the shipping company for the customs clearance and tax calculation. This is usually an amount that varies somewhat with the total price, say $15-40, so it's relatively cheaper on expensive than inexpensive items. That means a total cost of the $60 mech is $115-120 when imported to Norway. That is roughly double the original cost.
However, if the item is inexpensive (<200 NOK, or ca $40) there are no taxes charged and the companies aren't allowed to charge customs clearance commission since there are no taxes to pay.
So, for very cheap items it pays to buy overseas if you get cheap shipping and on medium range prices, like a mech, it is usually very expensive compared to abroad.
Why does the government want the tax? Well I guess it is so that Norwegian companies have a fighting chance on selling imported goods compared to simply buying from abroad. The Norwegian companies are obliged to charge these taxes when selling nationally, so that will even out the differences between buying from abroad or nationally. Sometimes it is still much less expensive to buy from abroad though.