My feeling is that:
B8's are the cymbal parents purchase children when giving their kids a shiny new drum set as a gift. They are pretty undesirable musically, but have their place as emergency-backup cymbals, loaners, house-kit-pies, etc. Half the forum members likely have a B8 or two in one of their closet/attic.
In terms of used pricing, B8 cymbals are pretty much "free", and I cannot recommend spending $300 to buy a new set. I would recommend saving another hundred bucks and looking for a set of used A's or AA's. If purchasing new is a must, an A391 set is a good reference approximation of what you should be looking for, which you can usually find for about $700. Occasionally, you'll find a decent cymbal pack on special/clearance for ~$500. This is why you see posts recommending quality/used cymbals. FWIW, I sold a A-Custom Boxed set for $500 a couple years back.