If you are talking sales to other domainers, I agree
@equity78 that most would command essentially nothing (the same applies to lots of other types of domains, of course). I had not read in the OP post that
@Jetheat was meaning for sale to other domainers, but I guess the OP can clarify if that was the meaning.
I have only four letter number combinations in almost 500 names in my portfolio, so it is not that I am enthusiastic on them. It is not something I routinely look for, and would not personally buy something random in either pure letters or mixed unless a huge deal. Interestingly I just posted a sale of a mixed .org this morning in report completed sales here.
As with any potential acquisition, I would be very hesitant about any acquisition for which one has no idea of end use. If it was LLNN and you can come up with a bunch of acronym applications for the LL I would consider it at the right price, and the background
@equity78 provides on more desired numbers is useful intelligence to further determine worth. For example if the letters were CC that to me could mean credit card, climate change, casino coin, etc. so I would view that as desired (also memorable since repeated_ whereas if the letters are ZQ the possibilities are less obvious to me.
Bob