Are expensive makeup brushes better? The answer is a resounding: Not necessarily.
I've been wearing makeup for 40 years, so I know my makeup. I also was an on-again off-again makeup artist from 1995 to 2005. So I know my makeup -- and my makeup brushes. Professional quality makeup brushes for the masses have become popular in the last 15-20 years. Only the uninformed or apathetic use the ridiculous little applicators that accompany eye shadows and blushes. Some companies, such as MAC, don't even bother to insult us with those at all and expect their customer to be savvy enough to use quality brushes.
My first investment in brushes in the early 1990s was truly a good one. Some of my MAC, Bobbi Brown, and Trish McEvoy brushes are still going strong. (I do wash them periodically with cleanser and water, but not too often since that can shorten their lives as well. I'm more likely to use a spray-on cleaner to get the surface grime off.) These brands were, and to some extent still are, the gold standard in makeup brushes.
More recently, however, many companies have launched much less expensive versions of brushes that mimic the shape and texture of the real deal. Some are natural hair and some are synthetic, but all are really, really good! The pro's reviews for both Sigma and Crown brushes are outstanding. My personal favorite is the newly launched, animal-friendly Real Techniques by Sam Chapman collection. This pixiwoo YouTuber has really put a lot of thought in to her brush line, as demonstrated by the color coded handles, perfect shapes, and luxurious-feeling bristles. Granted, these have only been around for a few weeks, so I cannot comment on the lifespan of the brushes. However, I can comment on the ease of makeup application and excellent assortment. I've stowed away my other brushes in favor of these since they are so uniformly pretty. Thank you, Sam!
My absolute favorite of Sam's brushes is the blush brush ($9.99). It's fluffy and tapered and applied the sheerest whisper of blush.
Her line also includes a powder brush, foundation brush, stippling brush, a set for eye application, a core set for a variety of uses, and a travel set, They are available exclusively at Ulta and are flying off the shelves.
For some incredibly detailed photos of the eye brushes, see The Unknown Beauty Blog.