low mileage is not that great on Boxsters. When these cars sit awhile it can cause the dreaded IMS problem
IMS Failures Explained | IMS Retrofit

It's better to have a 986 with 70,000+ mileage because the thinking is it's likely been driven regularly and usually IMS occurs on low mileage vehicles.

I just had my IMSB upgrade done because of this low mileage single row IMSB concern (2003 S). I bought the car in 2008 with 14k miles on it. Now with 25k on the clock the IMSB in my car was in perfect condition when I replaced it last month. I know it's only a single data point, but low mileage in my case was still a good thing. When I bought my car in 2008 it still smelled like a new car and the dealer mechanic that did the PPI said it was the cleanest used Boxster he'd ever seen as he looked at the car from underneath while it was on a lift. My 11 year old car is like brand new with this kind of low mileage and I would still recommend finding a good low mileage unit over a higher mileage car. You'll probably end up doing the IMSB upgrade in any event, so why not strive to find a car with as little wear on it as possible. Be patient and find the right car for you. Know what options are on your must-have list including your preferred color and then wait until the right car comes along.

For me, the options on my must have list were:
1. Glass rear window (meaning no older than 2003)
2. Manual transmission
3. Heated seats
4. Wind stop
5. Color (Seal Grey or on of the Silver colors)
6. Light colored interior
7. 18 inch wheels (colored crests were a nice bonus)
8. PSM (The onboard computer would have been a nice bonus that my car does not have.)
I didn't care about the stereo as I had read that even the Bose upgrade needs some work to sound good so I knew I'd replace the system in any event.

I would second this as I bought my 2001 Boxster base with 30k miles on it 2 years ago. It now has 41k miles on it. The accessories have not experienced the wear and tear of a 70k + mile car. I have had installed the IMS Guardian for the ims concern. Original water pump, AOS, coolant reservoir tank etc. Will replace them as they break.Have had done CV joints, replace coolant, accessory belt tensioner. Nothing major. Am a happy camper!

Ok, so, an update:

Drove a '00 S with about 43K on it. It was superb. It had wear but everything was intact save a few imperfections (lining on top undone in one place). The biggest thing to me is the low mileage.

I feel as if this is the one. This is the first one I could see myself buying. It was the first connection I had. HOWEVER, my budget may keep me out. Without a PPI, I said I would go $11,000. He was straight up with me and said he had $13,000 in his mind on the way over. Also said the dealership told him $12 without looking at the car.

I do not want to get emotional about it. I want to make a good decision. That said, I don't want to pass up a good deal just because I'm a thousand or so off.

What do y'all think?

Get a PPI and see what that says. It might give you some more negotiating leverage. Only you can decide what you are comfortable spending, but a good condition car that doesn't need much right away is better than a "cheaper" car that hasn't been properly cared for. You also need some cushion for any surprises. A 2000 S with that mileage and at that price is a pretty good deal IMHO. I paid $13,750 for my 2001 S a year ago with 64K miles and it was in excellent condition.

Get a PPI and use that to help negotiate.

Never believe what the seller says about what someone else offered him (he should have taken it if it was so great).

Turn your thinking around: Will the seller really want to lose a cash sale over $1,000? Force the seller to make the decision.

Therefore, if you really want the car, show up with cash and make your offer - if the seller declines, then walk away.

Do not get emotionally attached.

I'll say it again: do not get emotionally attached.

Its a buyers market, another equally good or better car will turn up at the same or better price within a short time.

Make sure that you have $2,000 left over after the purchase to fix whatever the owner "forgot" to mention or anything that happens to crop up in the first year of ownership. It is normal to need a few repairs on a 10+ year old car.

Get ready to own the best car of your life and start living the dream!

Ok so here's what I did:

Basically sent him an email explaining that I am a serious buyer and reminding him that he could have cash. Also mentioned the IMS problem explained to me by a Porsche mechanic (which I would be taking off his hands) and told him how Edmonds appraised the car (which is well below his asking point).

Don't know if this was the right move or not. Don't want to sound too desperate or arrogant. But, hey, I can still walk away if he balks. No harm.