If you've been holding off getting an ETA because you're not traveling until later in the year, you might want to reconsider.
The Home Office has apparently decided they should be charging more - legislation was introduced into Parliament this week proposes setting the maximum fee for an ETA at £16, up from £10.
It's not set in stone - the announcement mentions "the flexibility to increase the maximum fee", but it indicates a general plan to charge more.
This legislation is subject to a debate and a vote, and the fee increases will require further enabling legislation.
https://www.gov.uk/government/news/next-steps-for-a-more-efficient-immigration-system