Hi Accurate,
Kezion.com would be a 6L.com to start. Being of the brandable nature here is how I would appraise it:
Kezion.com Appraisal
Reseller Price: Reg Fee
End User: Mid XX-Low XXX (they would really need to be interested)
What I Would Pay: Reg Fee (not a bid)
Good Luck with the domain and to properly answer your question about 4L.coms would be difficult. Look up dnjournal.com and check the domain sales - those are generally end user 4L.coms selling in the low XXXX, but 4L.coms get tossed around in the low XXX range most of the time for resellers.
Cheers,
Kris