Not sure why bushing dies came up unless it was part of a set since they are re-sizing dies, not seating dies, and don't have anything to do with "crimp" but whatever, I'd like to throw in my 2 cents.

Bushing dies compress the case neck in one step to provide a desired "neck tension". Conventional dies reduce the neck size significantly below the desired size and then, by pulling the sizing button back through it, expand it to achieve the desired "neck tension". Bushing dies are considered to be superior in this regard as they minimize the "working" of the brass which should result in longer case life.

Another advantage is the bushing dies eliminate the need to lubricate the inside of the case necks. If not removed this lubricant can result in variations in neck tension. Importance varies with the application.

To turn or not to turn. Even premium quality brass varies in neck thickness. My most recent batch of Lapua 223 brass varies from .012 to .013 with some necks being .012 on one side and .013 on the other. Given a bullet diameter of .224 adding twice the neck thickness gives me a loaded round neck diameter of .248 to .250. If a .002 variation in neck tension is acceptable for your application then you can enjoy the extension in case life but you won't be seeing any improvement in accuracy.

A typical set of standard reloading dies costs around $30 including the sizing and the seating die.

A Redding Type-S sizing die from my supplier is around $55.
Each bushing costs about $12 ($25 if you go high-test), you'll need at least 2, maybe 3.
You will still need to buy a seating die.

K&M neck turning tool $44.
Mandrel for appropriate caliber $12.
Shell holder for turning tool $40

Neck expander with mandrel (used to prep case for turning) $22.

Yes, I do use bushing dies, along with a lot of other gadgets each with the potential (hopefully) to shave another .010" off my group sizes. Adding them all together my group sizes should be smaller than my bullets. Hasn't worked out that way yet.

Again, just my 2 cents. Your mileage may vary.