Once you reach Velen, you can swim directly to Novigrad or take a boat to get there. Then, exit the shop, talk to the merchant again, and he will have all the shells in stock again.

First, go to the merchant at the following location at Hierarch Square in Novigrad. You must buy shells from a merchant, dismantle them, and then sell the pearls for a higher price. This glitch allows you to earn over 1,000 crowns per minute. You can avoid patches being installed by disconnecting from the internet until you are ready for the game to install new patches. To avoid not being able to use this exploit, either do not install new patches before using this exploit or delete the patches. Note: This glitch was performed on an unpatched version of the game. You can also buy florens so he has more money, and then just convert florens to crowns at the bank in Novigrad. Alternately, go to the Loan Shark in Navigrad since his money comes back each time you leave. If you meditate for five days, the shops will get all their money (crowns) back.

Thus, stay under that number to avoid losing any crowns. Sell all the items you get from this exploit for lots of crowns. Turn the camera in a 360 degree circle or walk a short distance away from the nest, and then loot the nest again for all items to have respawned. You can leave any item, but you must leave one item or this will not work. Go to any monster nest, and loot everything in the nest except for one item.