Panasonic
Panasonic KXTCA60 telephone headset is listed on Ebay. It is new and listed at a low price. Shipping is free for this item.
The new Panasonic KXTCA60 telephone headset is reversible, can be used on either ear. It has a comfortable and lightweight design with 4-foot cord.
It is designed for use with any cordless phone.
Panasonic KXTCA93 telephone headset is listed on Ebay. It is new and
listed at a low price. Shipping is free for this item.
The new Panasonic KXTCA93 telephone headset is compatible for use on
left or right ear. It is a clip-on headset for cordless phone. It has
convenient volume control and mute switch. 
There are quite a few selections of telephone headsets on Ebay.Some are new and some are used. GN Netcom, Panasonic and Motorola are among many brands of headsets listed on Ebay.
Some of these headsets are even shipped out without charge. Sometimes they also come in a complete set that includes charger.It's even more convenient nowadays telephone headset chargers are available in many types such as car charger, wall charger or USB charger.
Some headsets may not work with certain telephones. Some chargers may not work with certain headsets.It's better to get the same brand of telephone headset and headset charger just in case.
It's also a good idea to get the whole set of telephone, telephone headset with the charger, receiver and adaptor.So sit back,relax and enjoy your new headset.