Costco offers its members the Panasonic DECT 6.0 2-Handset Expandable Dual Cordless Phone for $32.99. (Non-members pay $1.65 more.) With free shipping, that's among the least expensive such expandable cordless sets we've seen. This phone uses DECT 6.0 technology, which reduces interference with 2.4GHz devices (like wireless networks). It also features a speakerphone, expandability to up to six handsets, Caller ID, voice mail support, up to 5 hours of talk time, and more.