Also:
Neither the CRJ 900 or the B717 have the legs they want.
The A318 is a further cut-down of the A320 so is too heavy for it's size, and it costs ~ U$35M.
B737-600 has a similar price tag.
But the as-yet unbuilt Embraer will sell for around U$26M, and is designed for the size, with empressive seat-mile cost potential, and a whole lot more baggage and freight capacity than the rear-engined competition.
And the kicker of course is that the Brazilian government would dearly love to give Air Canada an interest-free loan to buy them; something that wouldn't happen for a Bombardier product. The entertainment value alone should be worth the price of admission.
all speculation of course, but... ;o)