RAM is pretty darn cheap. We both have 6GB (triple data rate).
I think we can move 6GB from one machine to the other and buy 12GB for one of us so we each end up with 12GB total.

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007611%20600006050%20600006078&IsNodeId=1&name=12GB%20%283%20x%204GB%29

12GB is ~60-70$

Gabe:

Motherboard ( Asus P6T Intel X58 Chipset CrossFire and SLI Supported w/7.1 Sound, Triple-Channel DDR3, Gb LAN, S-ATA Raid, USB 2.0, 3-Way SLI PCI-E MB 3-Way SLI )
Memory ( 6 GB [2 GB X3] DDR3-1600 Triple Memory Module Corsair or Major Brand )

Lu:

Asus P6T SE — Intel X58 Chipset CrossFire Supported w/7.1 Sound, Triple-Channel DDR3, Gb LAN, S-ATA Raid, USB 2.0, Triple PCI-E MB
6 GB [2 GB X3] DDR3-1333 Triple Memory Module – Corsair Value or Major Brand

Wonder if mixing DC3-1600 and DDR3-1333 is ok.