Lots of affiliate clicks, but almost no sales

I run a small independent comparison site for home batteries in the Netherlands. A calculator tells visitors which battery suits their situation best. No ad budget, just organic traffic from socials and Google.

The numbers:

• 200 to 250 visitors a day
• About 60% of the visitors finish the calculator. People are on average really happy with the result (I have a short survey running on the result page)
• About 18% of people who finish the calculator click through to a shop
• My main partner counted about 450 clicks and 1 sale (0.2%), while their other affiliates convert above 1.2%

The setup: 30 day cookie, last click attribution, a product that often costs over €1,500, and links to several shops side by side.

My theories: My site works perfect for orientation, after that people search for reivews, watch some Youtube video and never buy through my links and coupon sites grab the last click.

• Is this normal for high ticket products with a long decision cycle?
• How do you figure out whether you're losing credit or people just aren't buying?
• Any ideas to increase the conversion rate?