Upgrade My Car Or Buy New?

I own a 1987 190E 2.3 Auto 4D Sedan. I have about 150,000 miles on my car. I'm about to make a major decision on either getting a new car or upgrading mine. I regret that the car is automatic, it wasn't my decision when the car was bought. For my new car i'm looking at either a C320 Sport Sedan (manual) or a C32 AMG. So my first question is, upgrade my current car or buy a new one?

My second question is where the heck can i get performance parts for my car? I've looked everywhere for any engine upgrades. I can't find any superchargers available, or anything for that matter! I was considering buying a bigger engine that i can find performance parts for but that's gonna end up being a hassle cause it's gonna require a crapload of other replacements.

Any info or suggestions will be appreciated. Thanks!