Hello, I`m the guy who started the post here
I must say gargoyle firmware has the best internet filter so far.
It has some issues with https filtering, but I manage to bypass it with an Mikrotik firewall (rb951ui-2nd) configured as a web filter.
Gargoyle works fine on http protocol, but when it comes to https it lacks as long the address you want to filter uses a long ranges of ip`s.
This is not a commercial thread, but Mikrotik is the best choise for your needs, it cost about 60$.
So, at this moment I can block every http web site and whitelist only the https I want.
But, if your site is using http protocol gargoyle do the trick.
If it uses https and is not hosted on some big servers or too many ip addresses you must use Mikrotik firewall or similar.
You can start from here:
http://forum.mikrotik.com/viewtopic.php?t=71533
Hope this helps.