They are worth it.
Chapman bits are said to be great. (I have not had any, personally.)
Brownell's bits are very good.
Wheeler bits are okay.
Grace screwdrivers are ... easy to break. I really wish I could stand behind Grace and pump up a small American company. But all I can really say is that their warranty and customer service are great -- but that's because I've had to use them, multiple times.
If you're like L. Boscoe and don't like the 'universal' sets, go poke around on the Brownell's website. They occasionally offer gun-specific or category-specific Magna-tip sets, like "S&W revolvers", "US revolvers", "Marlin lever actions", "Winchester rifles", etc.