Canadian carrier Rogers has extended a number of key iPhone 3GS promotions -- originally set to expire today -- until September 15th, both under its own branding and that of Fido. A $500 subsidy is available to people who bought an iPhone 3G between July 11th and September 30th of last year, and also spend at least $100 per month. Eligible shoppers are penalized with a one-year contract extension.

A $250 subsidy is likewise burdened with a contract extension, but can apply to anyone who bought a 3G between July 11th and December 31st of last year. A popular $30 iPhone data plan, offering 6GB per month, has also been extended to September 15th. Rogers notes that FidoDollars can be used towards the purchase of a 3GS, after which Fido will top up an account by $100.

The extensions are likely connected to ongoing shortages in Canada, which have seen a relative trickle of iPhones flowing into Apple, Fido and Rogers stores. 32GB models may be especially difficult to find. Greater shipments may arrive as soon as next week however, and a Rogers spokeswoman promises that "rolling inventory" is on its way, with backorders being filled on a "priority basis."