I spent years with a Briel Java. It cost around £75, but was not up to the job. It would gradually clog up with ground coffee and have to be stripped down. After a few years the plastic had become brittle and it was beyond repair.
I use a grinder every day so felt it was worth buying a serious one. I bought this Mazzer about 7 years ago and it is as good as the day it arrived. It is so well built that I would be surprised if it failed in the next 50 years. One of the key points is the powerful electric motor which means it can grind the beans slowly and quietly. Smaller grinders grind so fast that they end up burning the coffee and create a bitter tasting espresso. The Mazzer has a powerful motor and a very consistent grind, which is easily adjusted so the flavour is not altered. I haven't had to strip it down yet, and may never have to.
If I have to be critical, I would say that the hopper seems a little cheap and fragile for such a robust machine, but mine is still fine after 7 years and they are easily replaced.
If comparing grinders or espresso machines, I recommend the Coffeegeek site for detailed reviews, although some of the people there clearly have too much time on their hands.