My expertise is Scala, "Big Data", some machine learning and AI, plus generic Java/Spring/etc experience. My last job used only Scala+Play from that list. They were willing to hire remote people from across the world because (I assume) it would cost even more to hire experienced Scala devs in SF.

BTW if you care about saving money then London's contracting market is IMO even better than working remotely for US firms. It's worse now with the pound going to the toilet after brexit referendum, and will probably soon be only a memory for us foreigners though.