Ask HN: What's the best/easiest software combo for software online store?

Just curious as to what produc/service I could use, to painless setup an online store to sell software license with immediate delivery

1) What Shopping cart product? 2) What merchant services? 3) What advertising can I use?

I am looking for the least expensive/efficient package, I have very little/not willing to spend much on the store.

If some of you have a good product from your startup, please recommend.

Best regards!!