Amazon offers an open-box pair of ELAC Uni-fi UB5 GEM Bookshelf Speakers, model no. UB51-BK-BLM, for $399.95 with free shipping. That's the lowest total price we could find by $99. Features include a 5.25" woofer and 46Hz to 25kHz frequency response.
Note: Although Amazon describes this item as new, it has cosmetic blemishes on the concentric driver. (It does not affect the performance.)