I feel I was had by an online seller

I hesitated about posting this but I was left with no other choice.

What do you do when you've made a purchase online (thru PayPal to be exact) and after 3 days you still haven't received the download link, don't hear from the seller and your emails go unanswered?

Last Wednesday I bought a software program that would allow me to design 300dpi graphics of ebooks, CDs etc... from [removed]. It was supposed to be a big one-day sale event and I had been receiving several alert emails leading up to the big day.

I've sent him my $50 PayPal receipt as proof of purchase but there's been nothing but silence on his end. I checked my junkmail folder and there was no message in there from him.

Could this be what I'm thinking?

Are there any remedial steps I can take in case of foul play?

Michael