Price Advice Needed - Parents 2000 Boxster

[mf168601]

So my parents have said that their hunter green 2000 Boxster is up for grabs.

Details
- Bought and used in Ohio since purchase
- Stored in garage w/ cover throughout the winters
- 10K miles
- No discernible marks of any kind - the interior and exterior are both nearly perfect
- No accidents and runs fine (mighty fine)

Request
- Researched prices and came up with (visited the sites listed on the Mike Focke site):
- Edmunds - $15,381 (PP); $17,364 (Dealer Retail)
- KBB - $18,575 (PP)
- NADA - $20,875 (Clean Retail), $22,150 (High Retail)
- Ebay (Completed Listings) - $18,200

I want to give them a fair price without going crazy. Any advice? I was thinking maybe between 19K and 21K?

Thanks in advance for the help. I hope to be a Porsche owner soon.