I have not run into anything of that nature for n2k. I think the bill of materials cost to build a display is not much different if you make it a single
purpose display, like just displaying a 3 digit depth
, or if you make it a multipurpose display, so the manufacturers are loosing interest in the single
purpose displays excepting some pricey units with high vis displays for race
boats. I've been watching eBay but it is rare to see a new n2K display go by for much less than $350.
Since the new 4.5" multipurpose displays do have nice functionality you might look and find you can display the info you want in a format you like using less than 4 displays and just put a blank bezel over one (or 2) hole(s) - not the most elegant solution but a reasonable way to reduce cost.