I've been using heygpt.chat to interact with GPT 4. Chats are stored locally (front-end sends requests directly to openAI, no servers in the middle) and I've never spent more than $4 in a month, usually under $2 if you're careful to not make long chats ,which context grows geometrically. If you make occasional use of GPT and don't mind lacking the integrations into other services, I'd recommend it. Much cheaper than the usual $20/mo fee to access GPT 4.