What is the chance on finding a calm border collie or aussie?

Your chances are highly unlikely unless you feel like putting in a lot of training and exercise. The reason the ones at the agility class aren't as high strung is because they get a lot of exercise. Border collies and aussies are high strung dogs meant to herd and be outside for a long period of time. My roommates were lucky enough to find a relatively calm border collie but it was mixed with a lab so that probably contributed to it's calmness. He still needed to be walked and everything but not as much as a regular collie. So for you, you might want to try a mix (i.e. border collie/ lab mix) you might have a better chance of it being less high strung