A quick update, before answering the questions:
We should be getting our phoneline sorted tomorrow, which will give us a phone number, and the ability to get ADSL, which will take at least a week to get activated, but hopefully within two weeks I'll have a nice proper 512k connection again. o/
Anyhow:
how much does it cost?
Nothing, so long as you keep the "Powered by Invision Power Board v1.1.2 © 2003 IPS, Inc." text.
I think it costs $500 to legally remove that.
How hard is it to skin it / integrate it?
Nice and easy. There are already plenty of skins available, or you can use the admin section to make your own, or you can edit the PHP/HTML yourself.
As for the spam block, there is a 10 second flood block on this forum (default is 30 second) which should work for logged-in users as well as guests, but other than that there is nothing to stop multiple posts by the same user, although you can get hundreds of plugins, there must be several that do that. Or write your own mod in PHP. Also, there is also the ability to [temp] ban/dock post count/etc people who are irritating.
Guest-access is entirely optional, the reason I've got it here is:
1) Convenience - I couldn't post this otherwise, neither could other people who don't like logging in from public machines.
2) Attraction - Sometimes people don't want to register straight away, so they might stick around as a guest until they decide they want the extra features that registration provides.
Anyhow, I think I've covered everything, and I have to go do various things now, so I'll shut-up.
