Just to play devil's advocate: Cheap and midrange tires can be more fun,
BECAUSE they have less grip. Stay with me here...
For example, the BRZ/FRS twins come with non-grippy tires because it's easier to slide the car around at lower speeds and have a bit more fun. Installing sticky tires certainly increases grip, safety, and improves lap times on the Nurburgring (and your local autocross or dragstrip), as it takes more speed to exceed the grip of the tires. But a cheap/midrange tire can exceed that grip level at lower speeds. Now, with the torquey ST, 1st and 2nd gear will have more dreaded wheespin, but going around turns should produce more grins per mile with the the uniquely tail happy nature of the front drive ST. Regardless of the grippiness of the tire, you still need to learn the limits of your particular setup so you don't slide off into a fire hydrant or a school bus stop full of kids.
A Focus ST with cheap or midrange performance tires can still handle and brake better than a large sedan or pickup truck with expensive tires. The difference between an expensive to cheap/midrange summer tire isn't as drastic as using Blizzaks in snow vs Goodyear F1's in the snow. Cheap/midrange performance tires won't be like wearing bowling shoes and sliding across a wooden floor. They won't turn your car into an unsafe death machine...
So, if you are less concerned with beating the guy at the stoplight next to you, installing a big turbo, or shaving off 1.7 seconds at your local autocross, then
MAYBE a cheap/midrange tire isn't such a terrible choice after all. Otherwise, get a sticky tire with a low treadwear rating if you feel that best fits your particular needs.
And now can begin the flurry of posts from people justifying why they spent $xxx per tire for the best possible grip in all potential scenarios that may never actually happen.