I only have 1 parking space, so my single car must be a daily driver. What alternatives to the 997TT do I have?

Only one parking space? Is it under cover? Is it secure? Do you have on street parking? If you answer "yes" I would suggest a GT 3 for the DE's and weekend drives. With the money you save over the other options get a daily driver like a Buick, etc. or maybe a pickup and park it on the street.