Amazon offers the Crucial 8GB PC3-12800 DDR3-1600 SO-DIMM Laptop RAM, model no. CT102464BF160B, for $38.99 with free shipping. That's the lowest total price we could find by $4, although we saw it for $2 less last week. It features a CAS latency of 11.
Newegg offers the Adata 16GB XPG V1.0 Series PC3-12800 DDR3-1600 240-Pin Desktop Memory, with two 8GB DIMMs in Red, model no. AX3U1600W8G9, for $79.98 with free shipping. That's the lowest total price we could find by $68 and the best deal we've seen for the pair. The XPG DRAM operates at 2,133MHz and 1.5~1.65V and features 9-9-9-24 timings, and an aluminum heat sink.