It's no secret that CHDK ports for new Canon Powershot cameras usually lag the release of those cameras by months or even years. This often makes it difficult to purchase a new supported camera in stores or online.
This can be a problem if you do not want to buy a used camera via eBay.
One option to consider is an official Canon refurbished model. These usually come with a warantee and (in my experience) will be indistinguishable from a brand new model.
Here's a link to the USA web site - I'm sure there are probably others : Shop USA Refurbished Powershot Digital Cameras
Currently great prices on the A800 and A1300 - both supported by CHDK.Update : reyalp
pointed out another useful link : Clearance Powershot Digital Cameras