I did the same thing, with several free Adwords vouchers I got from various places, as well as one Bing voucher. I preserved my data here: https://docs.google.

I did the same thing, with several free Adwords vouchers I got from various places, as well as one Bing voucher. I preserved my data here: https://docs.google.com/spreadsheet/ccc?key=0AupgXsRU8E9UdDg5TkF3RTNDU1J4UW92R0JXOTdMYUE https://docs.google.com/spreadsheet/ccc?key=0AupgXsRU8E9UdDg... TL;DR My cost per completed acquisition was $13 per 500MB referral; my actual total out of pocket cost was the ~$5 overall of where I overspent my promo. Combined with earlier referrals, I've maxed out at 18.25 GB of free storage.