I'm not a letter guy but here's some recent sales with k and z. Use with caution as these may be stock tickers, significant acronyms, etc.
Domain TLD SalePrice SaleDate SaleThru
ZMI com $2,300 Jan-06 SnapNames
PPZ com $2,600 Nov-05 GDNX
IBZ com $3,000 Aug-05 Sedo
PPZ com $3,128 Jun-05 SnapNames
ZRC com $3,400 Jan-06 SnapNames
ZPS com $4,300 Dec-05 SnapNames
KJU com $4,500 Jan-06 SnapNames
YEZ com $4,800 Apr-06 Enoms Club Drop
FJK com $5,600 Mar-06 Snapnames
KHK com $7,333 Jun-05 Sedo
TJK com $8,645 Aug-05 Sedo
TVK com $10,250 Apr-06 SnapNames
WTK com $13,000 Aug-05 Sedo
GMK com $13,350 May-06 SnapNames
YAZ com $15,163 Jan-06 Sedo
Cheers,
BidNo