It is not as much matter of supply and demand w/ 4LLL as it is quality, and if you are regging indiscriminately, just because the names are 4LLL.com, you are really rolling the dice.
There are always new acronyms popping up for new technology that are 4LLL. One way to drill down the search is to either find 4LLL that form acronyms or, more likely, predict a future acronym based upon research and a calculated guess.
Companies brand w/ 4LLL terms- sometimes they are the companies initials, other times, they are made up and/or suggestive of other words. ie, (off the top of my head), names like grfx, pixl, itex, plxy, vtek, wico, xyco, etcc.
Oh, and lest I forget, one of mine- TWKR com
26x26x26x26= almost a half millon possible combos -456,976 (a little less than half the total number of all .biz registrations), vs 17,576 possible 3LL combinations.
Some have very good potential, but the well is a large one.