I think there are other considerations. Like your conversion. Do you know you have a solidly converting marketing letter on your site? is your sales process effective? A lot of people will complain they got "screwed" when they bought traffic packages (i know, i used to sell pop unders too from a site called visitorsnow), but when I'd go check out their site, it was super confusing, no direction for the site visitor to take. Also consider is your offer the kind that has a broad appeal? If not, don't buy bulk popp under traffic, if so, maybe give it a try, but always... ALWAYS be sure to track results from every paid or free campaign you run. It doesn' hurt to collect data too and my shameless plug for my site is responsebooster.com which is free
