Last week, I went thru the Dad's pile of drill bits that had accumulated in the barn workbench drawer, all from 10 bit sets purchased over the years. I chucked every bit and drilled into some scrap steel, watching the chips and smoke coming from the bore, separating good from dull bits. The old Craftsman and Black & Decker bits, made in USA, have held up well and still cut very good...chinese bits from either brand were nowhere near as good and have been quick to dull or break, evidenced by the number of bits under 3/16" that were missing from each set.
Post Christmas tool sales are usually when new bit sets are picked up as it's been cheaper to get an entire set than to replace individual replacements. Factor in the cost of the drill doctor and the frequency that bits are used, and the way I figured it, it was cheaper to score drill bit sets on sale than to sharpen existing stock. Underlying this decision is the country of origin of bits...chinese bits rule the market now, and are not of very high quality, but cost is low. Dad asked me about buying a drill bit sharpener, I told him to avoid the cheapo HF variety, then showed him the 5 sets of usable drill bits I had organized, and he agreed that what we had was good enough for now...the fistful of dull, rusty bits I culled out went into the scrap metal bucket, almost all were chinese.
If I was in a position to snag a complete fractional and numbered bit set of high quality, I'd splurge for a good quality sharpener to maintain those bits. But as long as I have access to economy bits for little projects, it's hard to justify the expense of a decent sharpener when replacement bits are so cheap.