Intel generally keeps prices at similar levels, going as far back as
original Core 2 Duo.
E6300 = $183 -> Quad core i5 processor non-K (such as Core i5 3450, 3470)
E6400 = $216 -> Quad core i5 K unlocked (such as Core i5 2500K, i5 3570K)
E6600 = $316 -> Quad core i7 K unlocked (such as Core i7 2600K, i7 3770K)
E6700 = $530 -> Core i7 6-core 3930K
The actual price ranges barely change (maybe +/- $5-10).
So you can just imagine Haswell Core i5 locked for $183-195, Core i5 unlocked K for $216-230, Core i7 K for $316-340, something like that. In other words Haswell won't cost you more than SB/IVB. Of course since SB is older now, you can find 2500K for $159.99 at MicroCenter, $30 cheaper than i5 3570K. However, if you intend to keep your system for a while (which you seem to do), I think it's worth it that you wait 6 more months with this system and just get a faster GPU for now. If you sell the 6970 while it still has value and grab a
good 7950, it should overclock to 1150mhz. That's a good value upgrade after reselling your current card without spending a lot of $.