I am looking into quotes for a large custom made window. I am looking into Jeld Wen, American Craftsman 70 and Paradigm 8300. All are roughly the same price. Is it worth spending the extra cash on a more expensive window?

No, it will not make a difference.

Depends on your area and comps. On a cheap house any new vinyl is fine. On an expensive house I’ve down Andersen 200/400 and higher

Unless it is mid market to luxury, the average consumer is not that familiar with brands of windows. You should be fine picking the best value window. 

I am a licensed agent and own an REI company in Florida, the only clients I have ever had look at window brands were in the $700,000+ (Which is luxury in the FL panhandle) range.