Mltsao - If you're a CostCo member you should have received a summer passport to savings coupon book. There's a nice offer in there for a Uniden 2.4GHz cordless phone with 2 handsets I believe for around $79. I don't have my coupon book near me to verify that right now, I'll do that later and provide you with a link to the full specs and picture. If you are a CostCo memberr but don't have your coupon book, just visit the member services counter and they'll give you another.
Although I love Panasonic cordless phones I would stay away from their 2.4GHz models. If you want 900 MHz analog or digital then get Panasonic (it's what I own).
If you want 2.4GHz (which may or may not interfere with WiFi) get Toshiba or Uniden, they make excellent phones. I just prefer Panasonic's track record of reliability, the handset has been durable, it doesn't look ugly, the newest 900MHz models are very functional offering caller ID on the handset, dual keypads, speakerphone, headset jack, etc. all for well under $100.