Carmen: The Chardonnay is crisp, not buttery, and a terrific value at close to C$10. I have seen good reviews for their Cabernet reserve as well.
Casillero del Diablo: Part of the Concha y Toro family, the Casillero del Diablo line of wines are spectacular values - I have had the Cabernet (awesome), Carmenere, and Sauvignon Blanc, and all represent great values for the $$$.
Cousino Macul: A winery that always gets great value reviews from the media, I like their Antiguas Reservas Cabernet and Merlot.
Errazuriz: The Errazuriz Max Reserva Cabernet is a great value and widely available, and I have heard good things about the resto of their wines.
Escudo Rojo: A very nice Cabernet made by the Rothschild family. Tastes better than many Californians at twice the price.