Steve, never buy a Porsche on a "budget". It's a toy. No one needs a Porsche. Pay cash, and don't finance your purchase.
At the very most you only have about $18K to spend, more like $15K if you are conservative. Why? Because you need to keep back about $2-5K for sorting out your new purchase. Things like tires, updating maintenance, insurance, catching the mod bug. You don't want to become Porsche rich and cash poor. A quality PPI will catch a lot of stuff.....but not everything. You don't want buyers remorse.
Why an "S"? Lots of reasons. Sure more HP. And if you buy a base, and then want more HP's, they are very expen$ive to "add on" and suspect at best.
What do you plan to do with the car? Daily driver? First Porsche? What is your prior sports car experience? Do you do your own maintenance? Is your 401K fully funded? Are your children's college funds fully funded?
Have your house in order, and have fun on your planned purchase.
