MCM Electronics has 10 foot Ethernet patch cables
for $1.64 apiece. (Promo Code EMC144)
They also offer free ground shipping for orders over $200, so a bulk-order of 122 cables can get into these good peoples' hands with zero shipping overhead.
And for the frugal Home Theatre builders, MCM also has decent prices on HDMI cables and HDMI-to-DVI converter dongles. I've used them for years, as they carry a lot of unusual repair parts, like belts for turntables, vcrs, and cassette tape players.