Drill bits are just like knives. They are made of metal and designed to hold a cutting edge. And this edge is the important part!!! Having worked with metal most of my life, I have found that no matter the $$$, if it isn't sharp it isn't going to do the job you are expecting. However, a good bit, due to better alloy composition ($$$), will hold an edge longer than a cheaper bit. I would suggest try a sample of a variety of bits and see what suits you. I have seen guys use $$$ bits and watch them fail time and time again when trying to penetrate stainless steel yet a low buck bit gets the job done in the hands of someone else. In these cases, heat was the killer of the $$$ bits. There are a variety of factors which adds to the sucess or failure of a bit. Heat weakens metal and a weakened cutting edge will quickly roll; dull. The 3 major factors are: Drilling speed (no, one speed doesn't fit all!!)when excessive builds heat (If it's red, it's dead!!). Drilling pressure of which most use to much of builds up heat. The bits ability to evacuate material along it's flutes is also a factor. Material retention causes excessive heat build up. Air, albeit not the best does help to dissapate heat so whatever airspace can be gained by rapid chip removal is a plus to bit life. The cooler a bit stays while performing it's job, the longer it will keep an edge. Hardwoods, and even knots, burls, and other irregularities in any wood can cause heat build up and or a physical dulling of an edge. Another thing to watch for on bits used for drilling wood is pitch build up. This also adds to heat retention and also blocks one's view of the bit tip. Watch the bit tip for a bluish discoloration in the bit itself. This would mean that there has been some heat build up and it is time to sharpen the bit. The more heat is allowed to build up in the bit, the more material that needs to be removed when sharpening. There are other important factors when considering a drill bit for proper applications but heat is the major player no matter the job.
In a nutshell, learn the proper use of a drill bit and related tools, and sharpening of the bit. Then, if you have a bit that works for, you then you have a useful bit!
] Other than that, what Billy B. said is true. Stick with the sets and sharpen in a DD.
