C9 is giving good advice. Drill bits have a finite life that is affected by the material being drilled and how you use the bit. Unless you know how to sharpen a bit or have a GOOD sharpener, bits will dull with use....usually fairly quickly.

You can buy bits at MSC ( www.mscdirect.com ). They sell individual bits of all kinds. You want what is called "jobber" length bits for normal use.

Also, MYTOOLSTORE in Vegas sells the DeWalt pilot point bits:
http://www.mytoolstore.com/dewalt/dew02-09.html
These bits have a small tip to get the bit started. They are great for sheet metal use or for use on curved surfaces. We usually buy the bulk pack.

Instead of buying several drill indexes that have 110 bits (of which 84 you will never use) consider building a custom set tailored to your use. For instance, if you do a lot of 1/4-28 tapped holes, buy the tap drill size (No. 3) and the clearance drill size (f). You can make a holder from wood. This way, you buy two sizes for each tapped hole size that you typically use. Also, you can buy the clearance only for stuff like 1/2" bolts. You will want to buy multiple bits for your commonly used sizes.

Our guys make a wooden block (from a section of 2x4) that holds
the tap drill, the clearance drill, and the tap for each size in a row. Using a Sharpie, you label the row and VIOLA!, you have a handy holder.

Dont be tempted to by the Awful Freight stuff. Buy quality drills and they will pay for themselves.

mike in tucson