I am wishing you good luck on getting new tires. (check the Tire Rack for reviews). I had similar experiences with tire balancing as the reviewer had. I have the feeling that most shops have balancing machines that don't spin the wheels fast enough. I never had this issue in Germany and I remember that they spun the tires at much higher speeds. Here in the USA the perfectionist may need to go to a racing shop to get his everyday wheels properly balanced.
The Focus is definitely a very exceptional car. We had a 2001 ZX-3 with the large alloys and wide tires and we never had a problem at all with vibration from them (or anything else on the car). I'd opt for better tires even if you have to pay for them.
The Focus is only very slightly behind Consumer Reports top-rated Civic (which costs THOUSANDS more) and is several notches above the Corolla in quality and dependability.
Congrats on a very fine, reliable economy car with excellent handling and performance.
As for Goodyear Tires, most are nothing but chewing gum except for the Comfortreds I have on my car. They stay balanced, are unbelievably absent of squirm, make my Corolla more stable in wind and have cut the road noise by 50%. If you have Goodyear tires now, go to their factory Gemini store and they will usually work you a deal on the upgrade tires. Don't expect a lot though, cus the OEM stuff is cheap to begin with.
Re: Tires. Go to a pro shop. Also, do all 4 tires. It is possible that you have a bad rim. I know this from experience, and how aggravating it can be to have unbalanced tires. Just pay the extra bucks yourself. For new tires I highly recommend www.TireRack.com. Read the reviews. Often a local shop will almost match the cost from TireRack, and give you free rotation and balance.
I hope your Focus is still doing great. I just noticed that Ford has increased production of the Focus by 30% to handle the increased demand (sales were up 23% last quarter).
As for the tires, I just put a set of Khumo all weather AA traction-rated tires on my GM compact and I have NEVER seen such an amazing improvement in handling and braking!! It handles better than it ever has, no longer spins on fast take-offs, and stops in about 2/3 of the previous distance. I upgraded to a 2:15/60 size.
I knew nothing about Khumo except that they are included in many high-performance wheel packages for Mustangs (I own one of those also). They cost just over HALF of what a set of Michelins (which our other GM car has) does.
Don't let poor tires discourage your enjoyment of your Focus. Our 2001 ZX-3 was a really awesome little car and never required a single repair. It was so much better than our old Civic, there is no comparison.