When you email people, they are not interested in your passion or anything else. They have a problem. They want someone helpful to fix their problem without trying to sell them anything. That's it. Don't be too chummy, don't be too cold. Just be straightforward and helpful - like a guy fixing a computer.
If you are too friendly, you often lose the sale.
Also, being a human behind it is not a selling point. It's not a differentiator. It's just the expected thing. Your product is your selling point, don't try to sell anything else.
People want to know immediately what the price is - but people who are communicating with you are a LOT more likely to buy from you (assuming you know how to communicate with them).