I noticed that the byformica product prices in the EU amazon shops (particularly in the german amazon.de) add up in a very unfortunate way.
One 240ml Sunburst bottle costs 29€ (which is perfectly fine as it just hits the minimum requirement for free delivery) but then the liquid feeder (6 pack) costs 22€ which adds up to 51€.
There are amazon gift cards available for 25, 50 and 100€.
I think it would be perfect to offer a bundle containing a large 240ml Sunburst bottle and a liquid feeder 6pack for exactly the price of a 50€ gift card.