I love this topic and I know it all to well ;)
I work with small businesses Building Brand influence to increase sales on social media but I also Market info products like yours. I would ask: Do you have a specific process that people go through?

There are a few specific things I want to suggest off hand.
First and most importantly, though, is asking for the sale.
You have got to get comfortable stepping behind the cash register so to speak.
This question makes me smile and I had to reach out to you because I know exactly what you are talking about.

There are people that do well without having specific processes in place, they do it intuitively and without much skill. Those are few.

Most of us have to break through some self-limiting beliefs and hop behind the cash register and say/do some BOLD things simply because: People need to be told what to do.

It's great that you are talking to prospects and they are sounding eager. One small tweak that will most likely increase conversions is to simply say, "Okay great, are you by your computer now? I'll stay on the line to help you through the checkout process."

Schedule a follow up time or just call back in 3 days to "See how it's going." ;) Even if you KNOW they didn't buy. Sometimes people need reminded or something came up as soon as they hung up. If you look at it as a kind gesture, so will they. :) Have you tried this yet?

There are tons of directions we could go with this. I'll wait to see what your reply is.

Have a great day!