To rebuild or buy crate

Hey guys thought I would pass this by anyone who has the same question.....

I have this project I'm working on it's going to be a driver/ weekender.
Machine shop wants $12k to rebuild and dyno old block with new everything, then you see crate motors for for $6 - 7k like from Summit jegs or Blueprint.
Is it worth the 5- 6k difference for a custom build engine for a driver.
They say you get what you pay for so, are crate vendors building cheap motors with a warranty?
Not talking down any business, just wondering how they can do it.

Thanks.