That is an insane mark up, even if the part is non stock and needs to be ordered as a one off they must be making some serious profit. Have you tried shopping around?
It has been said before but FCA's policy over certain Maserati parts is despicable especially things like discontinuing items for older tipos
Reason why I said is certain parts is because they are not too dissimilar to the likes of BMW/Mercedes/etc... have you ever priced up parts at a BMW MD? Maserati aren't the only ones quoting Â£600+ for a water pump
Screwfix, Black Sicaflex in a cartridge, it is a colour match, it is it’s own glue and no prep needed. Apply enough volume and form the required shape by wetting your finger (spit it soapy water) and move it around as needed. Will take a couple of days to cure in this weather or 24 hours in a heated garage.