Here's some info from Manheim Auction that should help your wife cross over to your side. Buy it.

Vehicle Identification Search: Select Country:
US Year: 1998
Select Region: National
Make: PORSCHE
No Model: BOXSTER
Style: ROADSTER
Auction Averages Zeroes Indicate No Recent Auction Sales.
See "Transactions" For Week Ending Jan 29
Above Average Below Dec 2011 Aug 2011 Feb 2011
Sale Price $11,379 $8,175 $4,971 $7,163 $8,243 $7,367
Odometer 37,724 74,949 112,174 86,492 81,165 82,592

4 7 6 Average Auction Odometer 45000 Prices are based on more transactions than shown under 'Transactions', above.

Feb 3 - Feb 10 2012

Above Average Below

$12,000 $9,900 $7,800
Est. Retail $14,650 $13,250 $11,850