I've been building a site for offering content for sale but I need to be able to offer instant downloads when a purchase is made but have it be secured so that the download link doesn't just get passed around. I know there is software available to do this but much of it is more expensive than I can afford right now. Anyone know of an inexpensive program that will do this (free would be even better)?

If you need a free software for that , then the famous OsCommerce is right for you man. It has all that you need

I'll have to check that out. Is this just free or is it an open source software? I had never heard of it but you call it famous so that must mean it's good? I appreciate the answer.

OSCommerce is used to sell e-books alot isn't it? I think I've heard of that a couple times, but never really needed it so I didn't look further. It would seem there must be some way to do this free/cheap with all the people who sell e-books online.