Rear band questions

Not Redline, re-lined. If a double wrap is the way to go, why? A re-lined double wrap is $37 vs. a new Raybestos double wrap for $64

Nothing wrong with the re-lined band. Sold a lot of them over the years with very few issues with the product. There are some bands (the hemi-three piece comes to mind) that are only available relined.
Opinions vary, but a lot of builders I know say that unless it's a performance application, stay away from the Kevlar bands. One even told me the only thing Kevlar in his opinion was good for was stopping bullets.