In all honesty, the OP needs to at least double their spend for a good disc road frame.
I mean, $500CAD is only about $350USD or €312, which just won't get you much of anything.
At around $750, things get interesting, like the Kinesis Racelight 4S Disc:
Kinesis Racelight 4S Disc Frameset - Blue | ProBikeKit.com