Those JBL JRX's are a couple of leagues below any JTR.
Matter of opinion. I have heard both JTR T8 & JBL JRX. The JBL sound just as good IMO. Both are ugly as hell too.
And in terms actual cost, let's not compare a little one-man garage shop vs. Harman International and other giant manufacturers.
For example, if you owned a garage shop and wanted to buy a pair of Diamond tweeters, it might cost you $4,000 just for the tweeters. But it may cost B&W only $400.
Does that mean the $4000 diamond off-the-shelf aftermarket tweeter is better than the $400 B&W diamond tweeter?
So let's go back to the $800 JTR vs $250 JBL for fun. If you were to buy the parts for the JBL w/o mass volume discounts and in-house savings, it might cost you $1,000 to build the JBL.