You don't really need one, as others have said, but of course to restore a car to original status of course, you do!
I do notice I get a very dirty engine bay....And I've never had one.
I wonder why so many Of us don't have them??
Because some people try and cut costs then wonder why things start going wrong. Truly a dirty engine bay is false economy in my view. Especially if you're trying to sell the car.
I wouldn't touch a secondhand Alfa for that very reason. Compromise on the undertray, (First you wonder why it's not there), then you wonder about belts, general maintenance, oils, electronics etc. etc.) Lots of Alfas DO get thrashed and that's OK to a certain point if they are also well maintained.
Alfa put them there for a reason. NOT aerodynamics as many think,
I've spoken to plenty of maintenance guys who say you're mad to leave them off. I trust them rather than some fuzzy anecdotal musings on a newsgroup.
Cars aren't cheap to run. Alfas are definitely not a cheap way to buy a car that is above most road cars. I shake my head with disbelief when people talk about saving a few pounds using cheaper oils,tyres, belts , etc. The old saying on drinking champagne on a beer budget comrs to mind.