BuyDig via eBay.com has a daily hot deal on Sigma 17-50mm f/2.8 EX DC OS HSM lens.
Sigma 17-50mm f/2.8 EX DC OS HSM lens for Canon APS-C DSLRs – $429.00 – at BuyDig via eBay.com – Deal Expired
This is lowest price online for this lens, regular price is $569.00 at Amazon.com, B&H Photo Video, Adorama.com.