Instead of creating a free product, think about expanding it a little more and setting a small price for it, somewhere between $7 and $14. Now instead of driving traffic to your offer, you are going to get others to drive it for you.
Post your offer on some affiliate sites that allow you to set your product at 100% commission. You’ll attract a lot of affiliates this way. Now they are sending people to your list, and you don’t have to spend any money. They’re building your list at no cost to you.
The greatest thing about this method is that you are building a list of proven buyers. Proven buyers will be much more likely to buy your one time offer, and any other offers you send them down the line.