Based on the invite with the multi-colored bubbles that was sent out by Apple for the September 10 media event yesterday, it’s almost certain that it will also unveil the rumored lower-cost or cheap iPhone 5C alongside iPhone 5S.

But the most important question regarding iPhone 5C still remains; what is going to be the price of it?

According to recent reports, it has been speculated that since iPhone 5C will come with iPhone 5 internals in a plastic casing, Apple may discontinue iPhone 5 and continue offering iPhone 4S.

However, a new leaked document from Canadian carrier Telus (via MobileSyrup) has revealed that it will discontinue only the 32GB and 64GB iPhone 5 on September 28, just after the new iPhones are expected to be launched, but will continue offering the 16GB iPhone 5.

This could mean that Apple will replace the 16GB iPhone 4S with the 16GB iPhone 5 as the mid-range iPhone for $99 with a two-year contract, when it launches iPhone 5S.

If that happens then Apple could discontinue iPhone 4S, and launch iPhone 5C as the new entry-level iPhone this year, and offer it for free with a two-year contract or for $350-$450 without a contract.

It is important to note that Apple typically doesn’t share its product plans with carriers, so it is quite possible the carrier is planning these changes based on what Apple has done in previous years. For example: When it launched iPhone 5 last year, it discontinued the 32GB and 64GB iPhone 4S, and has been only offering the 16GB iPhone 4S.

Since iPhone 4S will be only device in the iPhone and iPod touch line up with a 3.5-inch screen and the 30-pin dock connector, it makes a lot more sense to discontinue it.

We don’t have to wait too long to solve this mystery. Any guesses?