B&H has the Tamron 18-270mm f/3.5-6.3 Di VC II PZ lens for $329 (reg. $449) in Canon mount. This is a 15x zoom providing the equivalent of a 28-419mm zoom range in 35mm format. It is compatible with Canon DSLRs that have an APS-C format sensor. Check it out here at B&H Photo.
