Located a site that sells cheap Maserati key fobs
www.aliexpress.com sell most Maserati keys but not for my 4200 just type in their search box Maserati key fob.
Aliexpress is like eBay (actually, more like Amazon marketplace) in China. Sellers are all China-based and items are more often shipped form China. Expect things to be non-genuine unless it's clear to you otherwise, and expect delivery to take a while.
Other than that, I've bought plenty from there, mainly Chinese items, such as phones made by Xiaomi, tiny Lego like microblocks models and 8bitdo gaming control pads.
It tends to be cheaper than eBay, perhaps as you are going a little more direct, and sellers are usually very polite if you have any issues - though polite becomes frustrating when it takes 30 messages to sort something out if you have a problem.
If you're looking at more expensive items, AliExpress standard shipping has never seen customs charges for me, though faster DHL / courier has.