Disclosure: i work @ Dell
You are missing the point on 2 socket EX combined with large memory, it makes a lot more sense to build a virtualization optimized, heavy duty 2 socket server on EX than what Cisco did with B250
1) The 6500 series EX procs are optimized for 2 socket, so the price is very attractive (esp. given all the cores/cache) vs. EP. This usage is exactly why 6500 series exists.
2) The extra cores, cache, IO, memory bandwidth, & RAS features of EX make it a natural fit for heavily virtualized workloads vs. Cisco's B250. A 2 socket EX w/16 cores can deliver a much more balanced system than B250 can.
3) You can get a nicely configured 16 core Dell M910 with 128GB of memory for around $13K at list. If the $10K starting price for B250 is without processors/memory, then 128GB of Cisco's "cheap" 4GB memory alone would add $11,360 based on your prices (then you'd need to add the processors too). Net is you have a much more expensive, lower performance solution in B250 vs. 2S EX like Dell's M910.
4) Also note that the 8GB DIMM price premium has dropped significantly since Cisco has launched this product. They love to keep using their inflated 4/8GB pricing to make the B250 economics look better, but that isnt reality anymore.
B250 is a great example of Cisco not understanding the server market dynamics, commodity costs, & what you can do with standard parts. They built a proprietary memory ASIC for 2S EP to solve a real problem (customers really do want 2S servers w/ lots of DIMMs to get mid/high memory configurations w/ less $$), but this problem was about to be solved in a much better way by Nehalem EX & innovative designs based around (e.g. Dell's FlexMem Bridge). Also in typical Cisco fashion it took them a while to even get the B250 shipping also. In addition the cost of 4/8/16GB DIMMs are coming down very quickly, making standard Westmere EP designs able to now cost effectively play in the 72GB-144GB space.
So now B250 gets squeezed from traditional 18 DIMM Westmere EP servers from the bottom and low cost 2 socket capable EX designs from the top. IMHO Cisco made a big mistake "not monkeying around" with 2S Nehalem EX.