Most of this talk about LLLL.com domains is a bunch of HOGWASH!
Sure, you can talk about prices and give examples all day long. You can cite who is selling what, and for how much. You can talk about how "X" is a premium letter in China. You can talk about domains that begin with, or end with whatever "premium" letters. You can talk about how "pronouncable" an LLLL.com is (most often pronouncable only after drinking a 6-pack of beer). You can talk about how good it is, having a Consonant-Vowel-Consonant-Vowel pattern. You can report stats and do whatever analysis you wish.
If you think the value of LLLL.com is going up, maybe that's just because the value of dot-com domains, in general, is going up.
You could similarly talk about 3-word, dotcoms. There are great 3-word combinations, and not-so-great 3-word combinations.
One thing I do like about LLLL.coms, is that they sometimes are given new meanings, with the creation of new companies, new medical terms, diseases, product descriptions, services, initials of couples - or anything else that can be acronymized with four letters, at which point any LLLL.com has the potential to instantly zoom in value.
I'm sure many people have sold domains in the $10 to $100 range, when the end-user buyer would have been prepared to pay $5,000 - or maybe much more.
The bottom line is, though LLLL.com is a distinctive category, the value of the domain is made on a case-by-case basis - and that is for all 456,976 combinations.
The value comes down to traffic, the revenue it earns or is projected to earn, what meanings and uses it may currently be known to have, and often, it is based on YOU, if you can negotiate the best possible deal for the domain - which may not be easy to pin down, and, if you do wait for the right buyer, that could possibly be a long time.
Now, with all of this being said, with me as the authority on LLLL.coms, this thread may now be closed.