Помогите с переводом на английский фразы: "более дешевый тарифный план". Имеется в виду подписка на сервис. Рассматривали варианты lower pricing plan / lower-priced plan, но все какое-то не то.

Это пойдет в Terms of Service для западных клиентов, поэтому не должно звучать коряво для носителей языка.

Thank you in advance!

Нет, но если смущает, замените на lower cost plan

What's wrong with 'a cheaper tariff plan'? The expression's often used by electricity/gas supply companies in their advertising and I can imagine them using it in more technical/legal documents, such as in their terms of service for customers.

'cheap(er)' doesn't sound простонародный at all, at least in UK English. It can sometimes be used disapprovingly in certain set expressions such as 'cheap and nasty' (meaning 'cheap and of poor quality') -- but that doesn't apply here. Usually it just means 'less expensive' / 'lower-priced' / 'lower-cost'. They all mean the same.

The antonym 'dearer' is slightly different in that it can sound a little colloquial -- so instead of this I would probably use 'more expensive' / 'higher-priced' / 'higher-cost' if it's for use in a legal document.

+ [greater/better] value

+ offering better savings

По-английски для энергетических компаний действительно сплошь и рядом cheapest tariffs

Для мобильных операторов

Cheapest mobile phone deals (choose.co.uk)