I thought a "Brera for the summer" is called an Alfa Spider! Sorry, I couldn't resist.
My Spider is a 2.2 and it isn't exactly a neck snapper, but it certainly is stylish. I would say it has sufficient power and I don't see that the 3.2 offers enough performance advantage to make it worth my while. Of course, other folks may have a different opinion, but that's what makes a horse race, right?
By the way, if you can't afford to own a 3.2 you can't afford the 2.2 either. Neither of these versions is an economy car by any standards..... well modern standards anyway. A Brera is an unnecessarily expensive car which also gets pretty poor fuel mileage. It's not exactly in the "super car as a toy" category, but if money is tight, a Brera (or Spider) of any flavor is a poor choice.
Now if you mean to say you can't justify the additional cost of buying and operating a 3.2 (as compared with a 2.2), then I would have to agree. I could "afford" a 3.2, but I can't see the value in it considering the way I drive these days and the high cost of fuel in Italy. Perhaps that's the same situation you find yourself in.