For most of the past 45 years I've tied my own, primarily bass & saltwater flies. However, over the last 4 or 5 years I've bought some flies too. Started out buying some to copy the pattern, but found some guys selling flies that were actually very well tied so bought more.
One fellow I found, actually has an excellent bass streamer he ties, not something I've seen in catalogs either. I tied commercially for awhile, so can appreciate what others are trying to do with their talent.
A couple of years ago I was going on vacation to the SC coast & wanted to make sure I had plenty of flies, but didn't have much time to tie. Just happens that Orvis, which I'm not particularly a fan of, was having a sale & selling flies for 50 cents each, including saltwater flies. So, I bought a bunch. They're not my own, but still good quality on good hooks & they won't go bad. Heck, I doubt I could have tied some of them for less than 50 cents with my time limits.
Whether I tie or buy is usually relative to my situation at the time I need the flies. I'll tie most of the flies I use, but don't mind buying good flies when I have a need to do so.