If it was me, I would not throw any more money at this - in fact I'd probably pause it and just do some more research into the type of customer and what they are really looking for, and once you have tweaked things then give it another whirl. I've made the same mistake of throwing away money on something that got lots of clicks and not many sales. It comes down to research and being much more targeted.
You might already have a good idea of who your customer is and what they actually are seeking, but perhaps you are just not presenting the information the way they need to see it - ie tailored enough to their real motivation for wanting to buy the product.
In my sig there's some Adwords material that might help narrow down what the problem could be and the best bit is you can get some
really great information from there for free.
Cheers!