With all the machine work I do, I can totally say that buy good quality tools. I can sneak by with cheap end mills sometimes, but when it comes to precision work, only the best tools need apply. A simple rough cut, fine , use a cheap tool. But something you want to be precise and look good. Spend the money. I have small .015 size end mills that run me $50 a piece. I use them for engraving. I tried using the cheaper ones and they were so off center ground that the engravings looked stupid.
So pay once and be happy.