I use gas but I've seen threads where guys have bought cheap kettles and used the elements from those, I also saw a thread recently where a guy bought an element that he formed to his kettle shape
It may not have been on here, if I can find it I'll post a link. Do a search on electric Biab.
Are you looking to buy from anywhere ??
I've a 30L kettle and I'm waiting for 50L one, and that's exactly my idea. I'm looking to buy from anywhere, as long as the shipping isn't more expensive than the element itself