I assembled an automatic watch for about 100£. I wanted to buy an automatic watch (I was planning on something reasonable, around 1k-3k) but none of the watches pleased me completely.

I bought a Miyota movement, a case, hands, a face, a leather strap and a bunch of tools. It wasn't easy to assemble it and there is definitely not a lot of documentation online, but it wasn't impossible either.

It looks great, it's exactly how I wanted my automatic watch to look like. Highly recommend the experience.