Here is a direct source for Autel.
Auteltech Shop offers original Autel diagnostic tools like Autel Maxisys,at a good prices, with real autel scanner reviews from users
www.auteltechshop.com
I am not the product expert. But, it looks like the ones that list "ECU" programming are the ones that are $2k+.
If you can't find something suitable that is already sitting at Chinacrdiags.com, cancel that and get refund.
If time is critical (or at least somewhat important to you), I would look to get a Tech 2 that is ready to go.
While the VXNano is a great option once it is installed and running... There is no way of telling how easy that process will go. You could end up farting around, trying to get the program running.
It really might be best to get a Tech 2 that is in stock and ready to ship. New or even used.
I would start with that OBD2 website and just get what you need and have it ready to go out of the box as soon as it comes in. And for $300 or so, we know what it can do, which is pretty near everything under the sun when it comes to our GM trucks.
www.obd2tool.com