[Perfectlap]

The spread is wide because prices vary so much by zip code. If you want to sell quickly put it on eBay with a buy it now price on the high side. Most likely it will not sell in the first listing but you'll get many offers offline especially if you include contact info. You can work out a deal that way and arrange to have the car picked up or shipped. Often, you get people who search by zip code and are close by. Don't be afraid to list it more than once the longer you wait the more bidders, the higher the price.

From what I can see, 3.2's go quickly if they are well maintained. The one downside is that you've got that prior accident. Still I would list it on the high side to see if there bidders who don't care or are just impulsive. Given the IMS/AOS/WP work you've done and options I'd put your car ~$13,500 to a buyer that doesn't want to spend hours looking for a car with the known Boxster issues addressed. For a backyard mechanic familiar with these cars they'll probably go lower but not much lower because they'll know that those are easily $5k in repairs.
Now that these cars are past the 11-15 year mark (s models), I'm finding that although there are a lot of Boxsters in the market, most have a ton of deferred maintenance which is a bigger problem than just the expense for the next owner, they're indicative of a car that was not well looked after engine wise.

tip: get the interior of the car professionally detailed and put in new floor mats. Get very nice pics taken in a scenic location with the top down.
These types of pictures pretty much guarantee that you'll reel in an impulse buyer if one is looking. I can't believe how many lousy pics I see in ads for perfectly nice cars.