Well being from the UK myself, that limits my options somewhat but not completely.

Thinking about it, if somebody could be bothered with the hassle (plus it would be quite illegal so naturally no-one here would even consider it), they could actually base a sustainable hyip upon this system. Although, it appears the scammers don't do too bad out of this arena already.
As for the prices of the signals, I assume the provider sets the price themselves, passing on a percentage to Collective. As far as I can tell the revenue the signal providers get is pure profit (ie doesn't cost anymore to send out more signals) so some might want to have few subscribers but charge loads, but others might try to increase their profit by setting the price low.