A Bushnell Elite 3200 is about twice the price of a Bushnell Trophy. Does that make it twice as good a scope?? A Bushnell 4200 series scope is 3x the price of a Trophy. Is it 3X better??? Says who? Just food for thought, so bear with me...
"Value" and "bang for your buck" are very subjective terms. If a Leupold Mark IV were a "better" scope than a NXS, it simply would cost more new and fetch more used on the open market. That's how these things work. Look on any shooting site's Classifieds and see what used Mark IVs are going for compared to used NXS' and take note of how long each take to sell...
It's also tough to compare the two, based on what each company offers. Reticle designs & illumination, glass quality, turrets, zero stops...etc, are not created equal. IMHO, NXS beats Mark IV handily in all categories. Ultimately its up to you (the buyer) to decide what you want from your scope and what each feature is worth to you...
In the upper tier of optics, NXS probably offers the most "bang for the buck", hence their popularity. Compare a $1500 NXS to a $3000 S&B and you'll see the value inherent in a Nightforce more clearly...