Yeah, Brent pretty much said it.
You have to take into account your OVERALL campaign EPC not just the offer EPC. For example, if you're clicks are $0.10 and your pre-lander CTR is 15% then the actual click cost to your offer is going to be much more. So the EPC would have to be greater than that.
For example, you're advertising in AU and the clicks are $0.30. You spend $100 for 333 clicks. Out of these clicks 15% click through to the offer (50 clicks) so your EPC is going to have to be above $2 (which maybe possible in AU but a more realistic EPC would be ~ $1.30). Doing this formula ahead of time will allow you to set many benchmarks on how your pre-landers should perform flow wise.