You can only catch Gugrusaurus on the Selbina <> Mhaura Ferry during Pirate Attacks, together with Sea Zombies. On a normal ferry ride you'll catch Titanictus and Ryuga Titans with this bait.
If you're after Gugrusaurus with Meat Balls, try the Mhaura <> Al Zahbi ferry. But better take your Albatross and Penguin Ring with you, the Gugrusaurus are way harder on that ferry.
The best way to maximize your profit is to farm the mats yourself obviously. Go to sky and farm 12 earth clusters, and can farm hare meat from Forest Hare in East Ronfaure very easily with some sort of TH.
For example on my server 1 stack of earth clusters go for 70k and 12 stacks of Hare Meat usually would go for 66k. and these will net you about 17.5 stacks of Meatballs.
So instead of spending 437k on 17 stacks of meatballs, and buy your own crystals and meat, you'd only be spending 140k.
