Subaru seems like a good bet. I'd go with the Legacy personally (IMHO one of the best cars for the price out there), but the Imprezza is a good car, too.
AWD cars by price:
$10,000 to $20,000
2009 Suzuki SX4 — $16,439
2009 Subaru Impreza — $17,495
2009 Subaru Impreza Outback Sport — $19,995
$20,000 to $30,000
2010 Pontiac Vibe — 20,275
2009 Pontiac Vibe — $20,475
2009 Toyota Matrix — $20,500
2010 Toyota Matrix — $20,760
2009 Subaru Legacy — $20,795
2009 Subaru Outback — $22,295
2009 Ford Fusion — $24,345
2009 Mercury Milan — $24,845
2009 Mitsubishi Lancer Ralliart — $26,490
2009 Mercury Sable — $26,970
2010 Ford Fusion — $27,435
2010 Mercury Milan —$27,800
2009 Ford Taurus — $28,520
2010 Ford Taurus —$29,020
2009 Dodge Charger — $29,790
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