Sure it is, just search for "LGA 2011 DDR3", the DDR3 bit to avoid the motherboards that aren't compatible, as they'll all have DDR4.
Here's one right off the bat:
http://www.ebay.com/itm/132014331623
Every time someone who has a Sandy Bridge - era Extreme series CPU updates to a newer build, and puts their X79 motherboard on Ebay, another one comes onto the market, so its basically self-replenishing.
Now the dual-CPU boards do seem to be more around $300, but I bet could be obtained at about $200 with patience (US dollars). But to get better performance than an i7 (for encoding, not gaming), you only need 1 of those CPUs.