iPhone water seal alternatives

Hello everyone, I’ve been repairing iPhones for a while and it has always been a struggle when ordering water seals to close up the iPhones when I am done repairing them. That’s because they are quite expensive for what they are (6€ with shipping) and take longer times to arrive. Does anyone know where I could purchase a lot of these cheaply? Are there any alternatives, like liquid adhesive? I was about to buy this one.

https://www.ebay.it/itm/186087598868?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=EIUYovJwQ9K&sssrc=4429486&ssuid=vyjj_mwxseq&var=&widget_ver=artemis&media=COPY

but I wasn’t sure if it was suitable for the purpose I’d want to use it… any advice is appreciated, thank you.