The UK has had 10-year biometric passports for some time. I believe that my renewal was $216 last time around, so $200 sounds about right. Plus Rerun's wife "is in the know".
Given the price difference, the only thing that you'd be saving is the "hassle" of renewing in 5 years instead of 10. I'm not sure that it makes it worth the potentially bigger hassle of trying to get back in as, technically speaking, a foreigner.