The 2000S is a wonderful car and, assuming you are getting it for a wonderful price, can be a joy to own.
Having said that, are there any service records available for the car that show the oil changed at least 3 times and preferably 7 times? The brake fluid changed recently?
Assume the tires are 7 years old and original. Plan on replacing them at a cost of $1000 for great tires or $800 for average ones. This based on the age of the tires, not their mileage. If the car was stored inside, then there may not be the age deterioration and you may get another year out of these but do change them when the rears get to 4/32".
Do get a PPI just so you learn more about the car and have an idea of what repairs and preventative maintenance will need to be done. If you are absolutely going to buy the car anyway, I'd suggest having a 60k service done on the car ($1,300 or so) just so you know in what shape everything is. That will take care of the belt and the inspections will take care of the hoses and similar things that could go wrong.
Some web pages that might help you include the buying guide and a list of local mechanics.
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The best deal you'll get is when it is the coldest out and no sane person would be interested in buying a convertible.