Hmmm interesting. If I can earn 100% on top of my initial investment, how much do you earn?
Ok, so lets say you also make $6 profit from my $6. Therefore you are getting 300% ROI in a couple of days.
Personally, I'd borrow $100 from somewhere (don't care where!), make $300 in 3 days, pay back the money (lets say $150), you'd still have $150 in 3 days. In 15 days you will have $4,050.
Now the reason why I say this, is I know how this sort of thing may work. Convince people to pay $6, they get $12 back. Then you say, well maybe give me a larger amount, you'll have your cash back in 3 days. Then lets say 3 or 4 people offer an average of $500, and then you run. $2000 in a week.