Dremels are good for a wide variety of applications, but as its been stated the bits are expensive and If you want to do any real precision drilling/milling/cutting using the aftermarket attatchments...forget it.
That said the adage you get what you pay for still applies as quality miniature precision presses/mills/cutters start around $800
If you are looking for something with more precision but cheap at the same time id reccomend Sonic Mini Tools Tho they are aimed at woodworkers a lot of his tools can be used just as effectively on metal.

Also, if anyone ha any access to the larger jewellery suppliers you might be cheaper getting your burrs/wire brushes/cutting discs etc from there, not to mention a much better range of different cutting/polishing grades.