I agree with leghog. I know that you have already doubled you're budget since the first thread, but I was on the same search you are on a couple of months ago. My budget was also $100, but I just couldn't find anything. So, I relectuantly raised my budget another 60 or so dollars and my options opened up quite a bit.
As for the presentation case backs, they seem to be present on the Seiko 5s, and then only on $2000+ time peices.
You also asked about duracoating the case. You can do it yourself, but I would reccomend against it. You would have to disassemble the watch to do so. You can send it off to multiple different companies to get it coated or bead blasted, but it is going to cost around $150 to do it.
Another thing is that water resistance is kinda weird. I've read on other forums that a 5 meter resistance doesn't mean that it can go down to five meters. That resistance would probably only be good for washing your hands or if it rains. I know that it doesn't make any sense, but if you Google watch water resistance chart, you should find some better info.
Also, 30ATM isn't 30 meters. ATM stands for atmospheres, so that watch should be able to withstand the pressure of 30 Earth atmospheres. I have no idea how many meters that is, but the aforementioned chart should help with this, too.
Anyway, as for the watch, I think that a SNK would be perfect. If you hate the face THAT much, you could always send it to a company and get it swapped for another one. But again, that will probably cost you more than the watch.
Good Luck! - Kris