It's a big investment, but they will last you a lifetime.
These sets
http://miponline.com/store/mip9512.html (SAE and Metric)get you the most popular and can be used with the driver of your choice, manual or power. They work great and take up little space in your pit box.
Think about this, you strip out a screw because of a cheap bit, then not only do you have down time, but the cost of getting the screw out. When someone brings us a car with a stripped screw at the store the first thing we do is grab the MIP stuff and usually it comes out. If not they get drilled or cut out.
I bought Integy stuff, broke them real fast, then dynamite, some broke, some lasted. Now I just use the dynamite handle for my MIP bits.