Tax & Title and that adds up to the car payments...
I would say a very high TCO (Total Cost of Ownership). There is a limit on how much you can borrow from a bank. I think is 60,000 and above you have to come with some cash to cover the difference. I would say, no bank will finance $100,000 car for 6 years )
It is completely dependent but most Porsche's hold their value and sell for more than your average car.
An old 356 will go in the $25k + range, a Boxster depending on milage will go from between $11k-60k, a new 911 will go for about $40k-$80k, and older 911's sell in the $25k-$40k range. Then there are the 944, and 928 that can be found between $1k-25k.
You also want to think, how much is it going to cost to maintain to drive. The cost of the vehicle is just the start, especially in high performance cars. You have simple costs as gas/oil/tires/brakes. Then you have regular maintenance and then there is unscheduled maintenance, and of course there is insurance.