Don't work them too hard & you'll be fine. The stuff on ebay that you can buy direct from China is pretty good for casual work. I don't know how they do it, but most of the sellers in China offer free or very low cost shipping. Just pick one with a lot of transactions & a high rating. Allow about 3 weeks to get here so buy when you don't need it. I've found that the dremel size stuff works just as well as the dremel in the package stuff at a fraction of the cost.